EP3718430B1 - Decorative element for an invisible setting - Google Patents
Decorative element for an invisible setting Download PDFInfo
- Publication number
- EP3718430B1 EP3718430B1 EP19167168.4A EP19167168A EP3718430B1 EP 3718430 B1 EP3718430 B1 EP 3718430B1 EP 19167168 A EP19167168 A EP 19167168A EP 3718430 B1 EP3718430 B1 EP 3718430B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- decorative element
- decorative
- setting
- approximately
- anchoring feature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000004873 anchoring Methods 0.000 claims description 90
- 238000000034 method Methods 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 26
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 239000000843 powder Substances 0.000 claims description 11
- 239000011230 binding agent Substances 0.000 claims description 9
- 238000005245 sintering Methods 0.000 claims description 7
- 238000005266 casting Methods 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 239000000049 pigment Substances 0.000 claims description 3
- 239000011029 spinel Substances 0.000 claims description 3
- 229910052596 spinel Inorganic materials 0.000 claims description 3
- 239000010437 gem Substances 0.000 description 28
- 229910001751 gemstone Inorganic materials 0.000 description 28
- 238000002844 melting Methods 0.000 description 11
- 230000008018 melting Effects 0.000 description 11
- 238000000465 moulding Methods 0.000 description 10
- 239000004575 stone Substances 0.000 description 9
- 239000002184 metal Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 238000000280 densification Methods 0.000 description 5
- 239000010440 gypsum Substances 0.000 description 5
- 229910052602 gypsum Inorganic materials 0.000 description 5
- 238000003754 machining Methods 0.000 description 4
- 230000000712 assembly Effects 0.000 description 3
- 238000000429 assembly Methods 0.000 description 3
- 229910010293 ceramic material Inorganic materials 0.000 description 3
- 241000579895 Chlorostilbon Species 0.000 description 2
- 230000003796 beauty Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000010987 cubic zirconia Substances 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 239000011021 lapis lazuli Substances 0.000 description 2
- 239000011022 opal Substances 0.000 description 2
- 229910052566 spinel group Inorganic materials 0.000 description 2
- 229910000906 Bronze Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000587008 Pachyphytum oviferum Species 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011014 moonstone Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000009700 powder processing Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000000135 prohibitive effect Effects 0.000 description 1
- 239000011028 pyrite Substances 0.000 description 1
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 description 1
- 229910052683 pyrite Inorganic materials 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000010981 turquoise Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- A—HUMAN NECESSITIES
- A44—HABERDASHERY; JEWELLERY
- A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
- A44C17/00—Gems or the like
- A44C17/04—Setting gems in jewellery; Setting-tools
-
- A—HUMAN NECESSITIES
- A44—HABERDASHERY; JEWELLERY
- A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
- A44C17/00—Gems or the like
- A44C17/02—Settings for holding gems or the like, e.g. for ornaments or decorations
-
- A—HUMAN NECESSITIES
- A44—HABERDASHERY; JEWELLERY
- A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
- A44C27/00—Making jewellery or other personal adornments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D25/00—Special casting characterised by the nature of the product
- B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art
- B22D25/026—Casting jewelry articles
Definitions
- the present disclosure relates to a decorative element, such as a gemstone, comprising an anchoring feature that allows the decorative element to be set within a decorative article, such as a jewellery piece, with an invisible setting, and to a method of making such a decorative element. Also encompassed is a decorative article, such as a jewellery piece, that incorporates said decorative element, and a method of making said decorative article.
- Decorative articles such as items of jewellery are often adorned with decorative elements. These elements may often be gemstones that require some form of setting such that they are held securely in place within the decorative article. There are many known ways to set a gemstone within a jewellery piece, with the type of setting chosen often influenced by the nature of the gemstone to be set.
- Transparent precious and semi-precious gemstones such as diamonds, rubies, sapphires, emeralds and cubic zirconia, are often carefully cut so that the gemstone has a multi-faceted surface; this is referred to as a facet cut.
- a facet cut Within a facet-cut gemstone, light is refracted inside the gemstone and reflected off the outer surfaces to create a pleasing optical effect.
- invisible setting is one such technique and involves setting a stone in such a way that the mounting for the stone remains unseen in the finished piece, with only a presentation portion of the gemstone visible to a viewer. This is in contrast to other common settings such as a prong setting, where prongs extend from a base to hold a stone in place, the prongs being visible above the presentation portion of the gemstone.
- the invisible setting effect is created by machining a groove into a lower portion the stone, into which a rail of an underlying metal framework can be fitted to hold the stone in place without the framework protruding.
- This type of setting allows the gemstone to be shown off particularly effectively, with no visible setting to distract the eye.
- the gemstones are typically set into the invisible setting using a cast-in-place method.
- a gemstones is set into a wax model of the article, with a rail of the wax model fitted into the groove in the gemstone, a gypsum mould is made around the wax model and gemstone.
- the wax is then burnt out, and molten metal is poured into the mould and allowed to set, leaving the gemstone set into the metal article.
- This 'cast in place' method is only possible if the gemstones have a sufficiently high melting point (i.e. higher than the melting point of the metal that will be used for casting).
- Gemstones such as diamonds, rubies, sapphires, emeralds and cubic zirconia that are typically used for facet cuts all have a sufficiently high melting point, meaning that facet cut gemstones are generally considered suitable for cast-in-place methods.
- Cabochons are typically manufactured with a flat back and usually glued into place. This is a cheap and straightforward process, and is effective for semi-transparent and opaque gemstones as they do not have the same reliance on light passing through the stone to enhance their beauty as transparent gemstones do. Gemstones that are typically cut into cabochons also typically have relatively low melting points, meaning that cast-in-place methods are not considered suitable for cabochons, and the gluing method is generally the most cost-effective alternative.
- the document KR20120049754 discloses a method of making a decorative element by moulding.
- the document KR200183269Y discloses a sintered decorative element with an anchoring feature.
- the process according to the present invention aims to solve at least some of the problems associated with the prior art.
- a method of making a decorative element for use in an invisible setting comprises a presentation portion, a base and a setting portion extending between the presentation portion and the base, with the setting portion comprising an anchoring feature.
- the method comprises providing a mould arrangement comprising: a mould, which comprises a presentation surface for forming the presentation portion of the decorative element and a setting surface for forming the setting portion of the decorative element; and a former for forming the anchoring feature, the former being located adjacent to the setting surface.
- the method further comprises arranging an element-forming material into the mould to surround the former and performing a heat treatment to form a decorative element with an anchoring feature.
- the element-forming material may comprise a powder, which may optionally be a ceramic powder, preferably zirconia (ZrO 2 ), alumina (Al 2 O 3 ) or a spinel.
- the element-forming material may also optionally comprise a binder, preferably an organic binder, and/or a pigment.
- the element-forming material may comprise a ceramic material and/or may optionally have a paste-like consistency.
- the paste-like consistency results in the combination of the powder with the binder
- the heat treatment may comprise a sintering step, which preferably comprises heating the decorative element to a temperature of between approximately 1000°C and approximately 1500°C, preferably approximately 1200°C for a time of between approximately 2 hours and approximately 20 hours.
- the sintering step provides densification of the ceramic powder, allowing for the reduction of internal surface area of the decorative element to produce a stronger final product more resistant to failure in compression.
- the heat treatment may further comprise a debinding step, which preferably comprises heating the decorative element to a temperature of between approximately 300°C and approximately 500°C for a time of between approximately 1 hour and approximately 10 hours.
- the debinding step drives off the binder and allows for initial densification of the powder precursor to form a green body that is suitable for sintering and further densification.
- the anchoring feature may be an opening or recess in the setting portion and the former may be arranged to protrude from the setting surface.
- the anchoring feature may be a protrusion on the setting portion and the former may be a recess in the setting surface.
- the former may be integral with the mould. This allows the mould to be made as one part, simplifying the assembly and manufacturing process.
- the setting portion may define the widest region of the decorative element, with the decorative element optionally having a height in a direction extending away from the base.
- the setting portion may define between approximately 2% and approximately 20%, preferably between approximately 3% and approximately 5%, of the height of the decorative element.
- the setting portion may have sides that are substantially perpendicular to the base.
- a dimension defined by the anchoring feature may differ from a dimension of the remainder of the setting portion adjacent to the anchoring features by at least 0.05 mm, preferably at least 0.25 mm.
- At least a portion of the presentation portion of the decorative element may have a substantially curved surface, and the base of the decorative element may be substantially planar.
- the decorative element may be a cabochon.
- a method for making a decorative article comprising a body and a decorative element set in the body with an invisible setting, made according to the method discussed above.
- the method for making the decorative article may comprise casting the body around the decorative element to engage the body with the anchoring feature of the decorative element to set the decorative element in place.
- the casting process may be a cast-in-place process.
- the invention also extends to a decorative element for use in an invisible setting made according to the method described above.
- a decorative element for use in an invisible setting.
- the decorative element comprises a presentation portion, a base and a setting portion extending between the presentation portion and the base, with the setting portion comprising an anchoring feature, wherein the decorative element is a sintered element and the anchoring feature is a moulded feature.
- a decorative article comprising a body and said decorative element, or a decorative element made according to the method discussed above.
- the body may be engaged with the anchoring feature of the decorative element to set the decorative element into the body in an invisible setting.
- the presentation portion of the decorative element may be substantially unobstructed by the body, while the anchoring feature, and optionally the setting portion, may be substantially shielded by the body, such that the anchoring feature, and optionally the setting portion, cannot be seen by an observer.
- the decorative article may be an article of jewellery, a watch or a decorative household item.
- Figure 1 illustrates a decorative article 10, exemplified here as a jewellery piece.
- the decorative article 10 comprises a decorative element 12, exemplified here as a gemstone, and a body 14 into which the decorative element 12 is set.
- the decorative article 10 of Figure 1 is a jewellery piece in the form of a pendant, but it will be appreciated that the decorative article could be any other jewellery piece, such as a bracelet, necklace, pendant, earring or ring, or may be another decorative article such as a watch or a decorative household item.
- Figure 2a shows a similar decorative article 10 in cross section, and reveals that the decorative element 12 comprises an anchoring feature 16, which engages with a corresponding anchoring feature 18 on the body 14 to set the decorative element 12 in place in the article 10.
- the anchoring feature 16 of the decorative element 12 of Figure 2a is a moulded anchoring feature, as will be described in more detail below.
- Figures 2b and 2c illustrates the decorative element 12 in isolation, and show that the decorative element 12 comprises a presentation portion 20, a setting portion 22 and a base 24.
- the presentation portion 20 is visible above the body 14 and unobscured from view, while the setting portion 22 and the base 24 are received within and shielded by the body 14, so that the element 12 is set in the article 10 with an invisible setting.
- the decorative element is a cabochon.
- the presentation portion 20 has a smooth appearance and has a curved surface, and the base 22 is substantially planar.
- the entire surface of the presentation portion 20 may be curved to define a convex surface, or alternatively only a part of the presentation portion 20 may be curved, with some regions being planar.
- the setting portion 22 is defined by the portion of the decorative element extending between the presentation portion 20 and the base 24. Sides 26 of the setting portion extend substantially perpendicularly between the base 24 and the presentation portion 20.
- the decorative element 12 defines a height h d rising from the base 24 to the uppermost point of the presentation portion 20.
- the setting portion 22 is relatively small compared to the presentation portion 20, and therefore has a height h p that is less than 50% of the overall height of the decorative element 12.
- the setting portion 22 may have a height h p that corresponds to approximately 5% of the height h d of the decorative element 12. In other embodiments, between 2% and 20% of the height h d of the decorative element 12 may be represented by the setting portion 22.
- the setting portion 22 comprises a main setting portion 28 and at least one anchoring feature 16 that can be used to set the decorative element 12 securely in place in use.
- each anchoring feature 16 is defined by a protrusion on the form of a lug that protrudes outwardly, away from the side 26 of the main setting portion 28.
- Four lugs 16 are included in total, positioned on two opposite sides of the main setting portion 28, with two lugs 16 on each side to define four anchoring features.
- the lugs 16 protrude from the main setting portion 28 by a distance that is sufficient to anchor the decorative element 12 securely in the body 14 when the decorative element 12 is set.
- the anchoring features may protrude from the main setting portion 28 by at least 0.05 mm and preferably by at least 0.25 mm.
- a dimension of the setting portion 22 in the region of the anchoring feature 16 differs from a dimension of the setting portion 22 in a region immediately adjacent to the anchoring feature 16 by at least 0.05 mm and preferably by at least 0.25 mm.
- the decorative element 12 is made from a material that can resist high temperatures.
- the decorative element 12 is made from a material having a melting point that is higher, preferably at least 20 °C higher, than the melting point of the metal that is to form the body 14 of the decorative article 10. In this way, the decorative element 12 can be set into the decorative article 10 using a cast-in-place method, as will be later described.
- the material of the decorative element 12 may therefore be selected to match the material of the body 14, or vice versa.
- the decorative element 12 is made from a material having a melting point that is higher than 1200°C.
- the decorative element 12 is made from sintered zirconia, though the decorative element 12 may be made from other materials, particularly other sintered materials, such as alumina, a spinel, or another suitable ceramic material.
- the body 14 of the decorative article 10 surrounds the entire setting portion 22 of the decorative element 12.
- the body 14 includes four anchoring features 18, defined by recesses, which are filled by the four lugs 16 of the decorative element 12.
- the co-engagement of the recesses 18 defining the anchoring features of the body 14 and the lugs 16 defining the anchoring features of the decorative element 12 prevents the decorative element 12 from falling out of the body 14 and sets it securely in place.
- Figures 3a and 3b show an alternative embodiment of the decorative article 110, which is substantially the same as the decorative article of Figures 1 , 2a and 2b , except for the form of the anchoring features. More specifically, in the embodiment of Figures 3a and 3b , the anchoring feature 116 of the decorative element is defined by a recess provided in the setting portion 122, which is engaged with a corresponding protrusion 118 that defines the engagement feature in the body 114 of the decorative article 110 (visible only in Figure 3a ). In this example, four recesses 116 are positioned on two opposite sides of the setting portion 122 of the decorative element 110, with two recesses 116 on each side to provide four anchoring points.
- Each recess 116 extends into the main setting portion 128 by a distance that is sufficient to hold the element 112 securely in place in the article 110.
- the recess 116 has a depth of at least 0.05 mm.
- a dimension of the setting portion 122 in the region of the anchoring feature 116 differs from a dimension of the setting portion 122 in a region immediately adjacent to the anchoring feature 116 by at least 0.05 mm.
- the body 114 of the decorative article 110 surrounds the entire setting portion 122 of the decorative element 112, with four corresponding anchoring features 118 of the body 114 in the form of protrusions extending into the four recesses 116 that define the anchoring features of the decorative element 112.
- the co-engagement of the protrusions 118 that define the anchoring features of the body 114 and the recesses 116 that define the anchoring features of the decorative element 112 prevent the decorative element 112 from falling out of the body 114 and sets it in place.
- FIGS 4a and 4b show yet another embodiment of the decorative article 210, in which each anchoring feature 216 of the decorative element 212 is defined by a recess in the form of an elongate groove that extends along a side of the setting portion 222 of the decorative element 220.
- the body 214 of the decorative article 210 again surrounds the entire setting portion 222, with two protruding anchoring features 218 of the body 214 filling the elongate grooves 216 such that co-engagement of the grooves defining the anchoring features 216 of the decorative element 212 and the protruding anchoring features 218 of the body 214 sets the decorative element 212 in place.
- FIGS 5a and 5b show a further embodiment of the decorative article 310, in which each anchoring feature 316 of the decorative element 312 is defined by a protrusion in the form of an elongate ridge that extends along a side of the setting portion 322 of the decorative element 312.
- the body 314 of the decorative article 310 again surrounds the entire setting portion 322, with two anchoring features 318, defined by elongate recesses in the body 314, being filled by the elongate ridges 316 such that co-engagement of the recesses 318 defining the anchoring features of the body 314 and the ridges 316 defining the anchoring features of the decorative element 312 sets the decorative element 312 in place.
- Figures 6a and 6b show a still further embodiment of the decorative article 410, in which the anchoring feature 416 of the decorative element 412 is defined by a protrusion in the form of a rim that extends around the entirety of the setting portion 422.
- the rim is flared to define a sloping upward-facing surface (i.e. a sloping surface that faces generally in the same direction as the presentation portion 420 of the decorative element 412).
- the setting portion 422 is widest nearest the base 424, at the bottom of the decorative element 412, and narrowest nearest the presentation portion 420.
- other rim shapes may also be used, for example in which the rim is not flared, but defines a flat upward-facing surface.
- the body 414 of the decorative article 410 again surrounds the entire setting portion 422, with an anchoring feature 418, defined by a correspondingly shaped recess in body 414, engaging the flared rim 416 of the decorative element 412, such that the decorative element 412 is set in place.
- FIGS 7a and 7b show a yet further embodiment of the decorative article 510, in which each anchoring feature 516 of the decorative element 512 is defined by a sloped protrusion 516 extending outwardly from the sides of the main setting portion 528 of the decorative element 512.
- Each sloped protrusion 516 has an upwardly-facing surface that slopes from the base 524 towards the presentation portion 520 of the decorative element 512.
- the body 514 of the decorative article 510 again surrounds the entire setting portion 522, with four anchoring features 516 of the body 514, defined by correspondingly sloped recesses 518, filled by the sloped protrusions 516 of the decorative element 512, such that co-engagement of the anchoring features 516 of the decorative element 512 and the anchoring features 518 of the body 514 sets the decorative element 512 in place.
- the decorative elements 12, 112, 222, 312, 412, 512 described above are made using appropriate mould assemblies.
- a mould assembly for making the decorative element of Figure 2b will now be described with reference to Figure 8a .
- the mould assembly 40 comprises a mould 42 and at least one former 44.
- the mould 42 comprises a mould body 46 having a moulding surface 48 that surrounds an interior moulding volume 50.
- the moulding surface 48 defines a presentation surface 52 which will form the surface of the presentation portion 20 of the decorative element 12, and a setting surface 54, which in combination with the former 44 will form the surface of the setting portion 22 of the decorative element 12.
- the formers 44 are responsible for forming the anchoring features 16 of the decorative element 12, and as such are a negative impression of the corresponding anchoring feature 16.
- the formers 44 are positioned such that they are located adjacent to the setting surface 54 of the mould 16, so as to form the anchoring formation 16 as part of the setting portion 22 of the decorative element 12.
- the mould assembly 40 is for use in forming the decorative element of Figure 2b and hence the formers 44 take the form of recesses in the setting surface 54, to allow formation of protruding anchoring features 16 of the decorative element 12 in the form of lugs.
- the recesses 44 have a depth of at least 0.05 mm, to form a corresponding protrusion 16 with a length of at least 0.05 mm.
- the formers 44 are integral with the mould 42 to form a unified mould assembly 40.
- the formers 44 may not be integral with mould 46 and may be separate components to the mould assembly 40.
- Figure 8b shows an alternative example of a mould assembly 140 for making the decorative element of Figure 3b , comprising a mould 142, which again comprises a mould body 146 having a moulding surface 148 surrounding an interior moulding volume 150.
- the moulding surface 148 defines a presentation surface 152 which will form the surface of the presentation portion 120 of the decorative element 112, and a setting surface 154, which together with the former 144 will form the setting portion 122 of the decorative element 112.
- the mould assembly 140 additionally comprises formers 144, located adjacent to the setting surface 154 to form the anchoring features 116 of the decorative element 112.
- the mould assembly 140 is for use in forming the decorative element 112 of Figure 3b , wherein the anchoring features 116 are recesses in the setting portion 122.
- the formers 144 in this example are protrusions that are provided on the setting surface 154 to protrude into the moulding volume 150.
- the protrusions 144 have a length of at least 0.05 mm, preferably at least 0.25 mm to form a corresponding recess 116 in the decorative element 112 with a depth of at least 0.05 mm, preferably at least 0.25 mm.
- the formers 144 in Figure 5a are integral with setting surface 154 of the mould assembly 140.
- the formers 144 may be provided as separate insert pieces that can be inserted into the mould 142.
- the configuration of the formers can be adapted as necessary so as to form differently shaped anchoring features, such as the anchoring features of the decorative elements of Figures 4b , 5b , 6b and 7b .
- the formers take the form of protrusions provided on, or recesses provided in, the setting surface of the mould, the protrusion or recess being any suitable shape or size.
- an element-forming material that will form the decorative element 12 is first provided, in the form of a feed stock.
- the element-forming material comprises a powder; in this example, the powder is powdered ZrO 2 (zirconia), though it will be appreciated that other suitable powders may be used, such as other powdered ceramics, including powdered alumina (Al 2 O 3 ) or powdered spinels, particularly transparent spinels.
- the powdered zirconia is mixed with a binder, such as an organic binder, and optional additives such as pigments, to form the element-forming material.
- a binder such as an organic binder
- optional additives such as pigments
- the resulting element-forming material has a paste-like consistency.
- the element-forming material is then poured into the mould assembly 40 so as to fill the moulding volume 50.
- the element-forming material is packed against the presentation surface 52 and setting surface 54 of the mould 42, and is also packed around and into the former 44, such that the element-forming material takes the desired form of the decorative element 12, including the anchoring feature 16.
- the heat treatment comprises an initial debinding step, which provides initial densification and drives off the binder.
- the debinding step comprises heating the element-forming material inside the mould to a temperature of between approximately 300 °C and 500 °C for a time of between approximately 1 hour and 10 hours to form a green body.
- the heat treatment additionally comprises a sintering step, in which densification is completed and a blank is formed.
- the sintering step comprises heating the green body to a temperature of between approximately 1000 °C and 1500 °C, preferably approximately 1200 °C for a time of between approximately 2 hours and 20 hours.
- the blank is then de-moulded, and finally, undergoes a surface finishing treatment to create the finished decorative element 12.
- the anchoring feature 16 is a moulded feature.
- the anchoring feature 16 is thereby formed as an inherent part of the process of making the decorative element 12, without the need for a separate machining step to make the anchoring feature 16, which would otherwise be labour and cost intensive. In this way, a decorative element 12 with an anchoring feature 16 can be made particularly quickly, efficiently and cost effectively.
- cabochons are generally inexpensive compared to materials used for facet cut stones. Machining an anchoring feature is a comparatively expensive process, and thus would increase the cost of a cabochon significantly. As a result, cabochons are not typically used in invisible settings, as the cost of providing the required anchoring feature is prohibitive.
- the anchoring feature 16 that is essential for providing an invisible setting can be formed in a cost-effective way in a relatively inexpensive cabochon element, thereby allowing a cabochon element to be used in an invisible setting without adding prohibitively to the cost of the article.
- the decorative element 12 is a sintered element, made of a material with a relatively high melting point.
- the cast-in-place method can be used to set the decorative element into a decorative article, as will now be described.
- the body 14 of the decorative article 10 is typically made of a metallic material, such as silver, gold, bronze, copper, steel, aluminium, or another suitable casting metals or alloys.
- liquid wax is first injected into a rubber mould to form a wax model of the body 14.
- the decorative element 12 is then positioned on the wax model as it would be in the finished decorative article 10.
- the wax model is then placed in a crucible and filled with investment, typically in the form of gypsum, which surrounds the wax model and the decorative element 12.
- the crucible, containing the gypsum, wax model and decorative element 12 is the heated in an oven, typically at a temperature between approximately 650°C and 750°C for a time of between approximately 1 and 3 hours to burn out the wax while leaving the decorative element 12 in place.
- the space left by the wax is filled by pouring in molten metal into the mould to surround the decorative element 12 and form the body 14.
- the crucible, now containing the gypsum, metal and the decorative element 12 is then allowed to cool before being placed in water to dissolve the gypsum, leaving the now-solidified body around the decorative element 12.
- the body 14 is polished and finished to leave the completed decorative article 10.
- the decorative element 12 need not be made and set into the decorative article 10 in the same manufacturing location. Instead, a first stage in which the decorative element 12 is formed may take place in a first manufacturing location, and a second stage in which the body 14 is cast around the decorative element 12 to form the decorative article 10 may take place in a second manufacturing location different to the first.
- the cast-in-place method made possible by the relatively high melting point of the decorative element 12, allows a fast and cost-effective method of setting a decorative element 12 into an invisible setting.
- the cast-in-place method also provides a particularly secure setting of the decorative element 12 in the decorative article 10, providing a high-quality finished product that is resistant to normal wear.
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Description
- The present disclosure relates to a decorative element, such as a gemstone, comprising an anchoring feature that allows the decorative element to be set within a decorative article, such as a jewellery piece, with an invisible setting, and to a method of making such a decorative element. Also encompassed is a decorative article, such as a jewellery piece, that incorporates said decorative element, and a method of making said decorative article.
- Decorative articles such as items of jewellery are often adorned with decorative elements. These elements may often be gemstones that require some form of setting such that they are held securely in place within the decorative article. There are many known ways to set a gemstone within a jewellery piece, with the type of setting chosen often influenced by the nature of the gemstone to be set.
- Transparent precious and semi-precious gemstones, such as diamonds, rubies, sapphires, emeralds and cubic zirconia, are often carefully cut so that the gemstone has a multi-faceted surface; this is referred to as a facet cut. Within a facet-cut gemstone, light is refracted inside the gemstone and reflected off the outer surfaces to create a pleasing optical effect.
- A variety of techniques are used to set such transparent facet-cut gemstones within jewellery pieces, all of which are well known in the state of the art. invisible setting is one such technique and involves setting a stone in such a way that the mounting for the stone remains unseen in the finished piece, with only a presentation portion of the gemstone visible to a viewer. This is in contrast to other common settings such as a prong setting, where prongs extend from a base to hold a stone in place, the prongs being visible above the presentation portion of the gemstone.
- The invisible setting effect is created by machining a groove into a lower portion the stone, into which a rail of an underlying metal framework can be fitted to hold the stone in place without the framework protruding. This type of setting allows the gemstone to be shown off particularly effectively, with no visible setting to distract the eye.
- The gemstones are typically set into the invisible setting using a cast-in-place method. According to this method, a gemstones is set into a wax model of the article, with a rail of the wax model fitted into the groove in the gemstone, a gypsum mould is made around the wax model and gemstone. The wax is then burnt out, and molten metal is poured into the mould and allowed to set, leaving the gemstone set into the metal article. This 'cast in place' method is only possible if the gemstones have a sufficiently high melting point (i.e. higher than the melting point of the metal that will be used for casting). Gemstones such as diamonds, rubies, sapphires, emeralds and cubic zirconia that are typically used for facet cuts all have a sufficiently high melting point, meaning that facet cut gemstones are generally considered suitable for cast-in-place methods.
- In contrast to the facet cut employed for transparent gemstones, semi-transparent and opaque gemstones such as opal, lapis lazuli, turquoise, onyx and moonstone are often cut and polished into a cabochon, which leaves the presentation portion of the stone with a smooth, flat finish. For stones such as opal, which often displays many colours, or lapis lazuli, which may have pyrite inclusions, such a finish is often the best way to show off the natural beauty of the gemstone.
- Cabochons are typically manufactured with a flat back and usually glued into place. This is a cheap and straightforward process, and is effective for semi-transparent and opaque gemstones as they do not have the same reliance on light passing through the stone to enhance their beauty as transparent gemstones do. Gemstones that are typically cut into cabochons also typically have relatively low melting points, meaning that cast-in-place methods are not considered suitable for cabochons, and the gluing method is generally the most cost-effective alternative.
- However, cabochons that are glued into place are often not stable and can fall out of the setting. Design restrictions for jewellery pieces can also often rule out options for other conventional settings used for transparent gemstones. The document
KR20120049754 KR200183269Y - The process according to the present invention aims to solve at least some of the problems associated with the prior art.
- According to a first aspect of the invention, there is provided a method of making a decorative element for use in an invisible setting. The decorative element comprises a presentation portion, a base and a setting portion extending between the presentation portion and the base, with the setting portion comprising an anchoring feature. The method comprises providing a mould arrangement comprising: a mould, which comprises a presentation surface for forming the presentation portion of the decorative element and a setting surface for forming the setting portion of the decorative element; and a former for forming the anchoring feature, the former being located adjacent to the setting surface. The method further comprises arranging an element-forming material into the mould to surround the former and performing a heat treatment to form a decorative element with an anchoring feature.
- By using a mould to form the anchoring feature, costs associated with machining like anchoring features for invisible settings can be eliminated, and an anchoring feature can therefore be provided inexpensively. As a result, it is economically viable to provide an anchoring feature in a relatively inexpensive decorative element. Such a method also allows for great flexibility in the shapes that the decorative element can form whilst still supporting an anchoring feature.
- The element-forming material may comprise a powder, which may optionally be a ceramic powder, preferably zirconia (ZrO2), alumina (Al2O3) or a spinel. The element-forming material may also optionally comprise a binder, preferably an organic binder, and/or a pigment.
- The element-forming material may comprise a ceramic material and/or may optionally have a paste-like consistency. The paste-like consistency results in the combination of the powder with the binder
- By using a ceramic material, further processing routes are made available when making a decorative article comprising the decorative element due to the high melting point of many ceramics. Many ceramic compounds are readily available as powders at low cost.
- The heat treatment may comprise a sintering step, which preferably comprises heating the decorative element to a temperature of between approximately 1000°C and approximately 1500°C, preferably approximately 1200°C for a time of between approximately 2 hours and approximately 20 hours.
- The sintering step provides densification of the ceramic powder, allowing for the reduction of internal surface area of the decorative element to produce a stronger final product more resistant to failure in compression.
- The heat treatment may further comprise a debinding step, which preferably comprises heating the decorative element to a temperature of between approximately 300°C and approximately 500°C for a time of between approximately 1 hour and approximately 10 hours. The debinding step drives off the binder and allows for initial densification of the powder precursor to form a green body that is suitable for sintering and further densification.
- The anchoring feature may be an opening or recess in the setting portion and the former may be arranged to protrude from the setting surface. Alternatively the anchoring feature may be a protrusion on the setting portion and the former may be a recess in the setting surface.
- In certain embodiments, the former may be integral with the mould. This allows the mould to be made as one part, simplifying the assembly and manufacturing process.
- The setting portion may define the widest region of the decorative element, with the decorative element optionally having a height in a direction extending away from the base. The setting portion may define between approximately 2% and approximately 20%, preferably between approximately 3% and approximately 5%, of the height of the decorative element. The setting portion may have sides that are substantially perpendicular to the base.
- A dimension defined by the anchoring feature may differ from a dimension of the remainder of the setting portion adjacent to the anchoring features by at least 0.05 mm, preferably at least 0.25 mm.
- At least a portion of the presentation portion of the decorative element may have a substantially curved surface, and the base of the decorative element may be substantially planar.
- The decorative element may be a cabochon.
- A method is also provided for making a decorative article, the decorative article comprising a body and a decorative element set in the body with an invisible setting, made according to the method discussed above. The method for making the decorative article may comprise casting the body around the decorative element to engage the body with the anchoring feature of the decorative element to set the decorative element in place.
- The casting process may be a cast-in-place process.
- The invention also extends to a decorative element for use in an invisible setting made according to the method described above.
- According to another aspect of the invention, there is provided a decorative element for use in an invisible setting. The decorative element comprises a presentation portion, a base and a setting portion extending between the presentation portion and the base, with the setting portion comprising an anchoring feature, wherein the decorative element is a sintered element and the anchoring feature is a moulded feature.
- There may be provided a decorative article comprising a body and said decorative element, or a decorative element made according to the method discussed above. The body may be engaged with the anchoring feature of the decorative element to set the decorative element into the body in an invisible setting.
- The presentation portion of the decorative element may be substantially unobstructed by the body, while the anchoring feature, and optionally the setting portion, may be substantially shielded by the body, such that the anchoring feature, and optionally the setting portion, cannot be seen by an observer.
- The decorative article may be an article of jewellery, a watch or a decorative household item.
- Features of any aspect or embodiment may be applied, alone or in appropriate combination, with other aspects and embodiments.
- Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
-
Figure 1 is a perspective view of a decorative article in accordance with an embodiment of the invention; -
Figure 2a is a cross sectional view of a decorative article in accordance with another embodiment of the invention, andFigures 2b and 2c are plan views from above and side views respectively of the decorative element of the decorative article ofFigure 2a ; -
Figures 3a ,4a ,5a ,6a and7a are respective cross sectional views of articles according to other embodiments, andFigures 3b ,4b ,5b ,6b and7b are corresponding plan views from above of decorative elements forming parts of the decorative articles ofFigures 3a ,4a ,5a ,6a and7a ; and -
Figures 8a and 8b are perspective views of mould assemblies for making the decorative elements ofFigures 2b and3b respectively. -
Figure 1 illustrates adecorative article 10, exemplified here as a jewellery piece. Thedecorative article 10 comprises adecorative element 12, exemplified here as a gemstone, and abody 14 into which thedecorative element 12 is set. - The
decorative article 10 ofFigure 1 is a jewellery piece in the form of a pendant, but it will be appreciated that the decorative article could be any other jewellery piece, such as a bracelet, necklace, pendant, earring or ring, or may be another decorative article such as a watch or a decorative household item. -
Figure 2a shows a similardecorative article 10 in cross section, and reveals that thedecorative element 12 comprises ananchoring feature 16, which engages with acorresponding anchoring feature 18 on thebody 14 to set thedecorative element 12 in place in thearticle 10. Unlike the anchoring features of the prior art, which are machined features, the anchoringfeature 16 of thedecorative element 12 ofFigure 2a is a moulded anchoring feature, as will be described in more detail below. -
Figures 2b and 2c illustrates thedecorative element 12 in isolation, and show that thedecorative element 12 comprises apresentation portion 20, a settingportion 22 and abase 24. As best seen inFigure 2a , when set into thebody 14 of thearticle 10, thepresentation portion 20 is visible above thebody 14 and unobscured from view, while the settingportion 22 and the base 24 are received within and shielded by thebody 14, so that theelement 12 is set in thearticle 10 with an invisible setting. - In this example, the decorative element is a cabochon. In this way, the
presentation portion 20 has a smooth appearance and has a curved surface, and thebase 22 is substantially planar. The entire surface of thepresentation portion 20 may be curved to define a convex surface, or alternatively only a part of thepresentation portion 20 may be curved, with some regions being planar. - The setting
portion 22 is defined by the portion of the decorative element extending between thepresentation portion 20 and thebase 24.Sides 26 of the setting portion extend substantially perpendicularly between the base 24 and thepresentation portion 20. - The
decorative element 12 defines a height hd rising from the base 24 to the uppermost point of thepresentation portion 20. The settingportion 22 is relatively small compared to thepresentation portion 20, and therefore has a height hp that is less than 50% of the overall height of thedecorative element 12. For example, the settingportion 22 may have a height hp that corresponds to approximately 5% of the height hd of thedecorative element 12. In other embodiments, between 2% and 20% of the height hd of thedecorative element 12 may be represented by the settingportion 22. - The setting
portion 22 comprises amain setting portion 28 and at least oneanchoring feature 16 that can be used to set thedecorative element 12 securely in place in use. In the embodiment ofFigure 2b , each anchoringfeature 16 is defined by a protrusion on the form of a lug that protrudes outwardly, away from theside 26 of themain setting portion 28. Four lugs 16 are included in total, positioned on two opposite sides of themain setting portion 28, with twolugs 16 on each side to define four anchoring features. - The
lugs 16 protrude from themain setting portion 28 by a distance that is sufficient to anchor thedecorative element 12 securely in thebody 14 when thedecorative element 12 is set. For example, the anchoring features may protrude from themain setting portion 28 by at least 0.05 mm and preferably by at least 0.25 mm. Said another way, a dimension of the settingportion 22 in the region of the anchoringfeature 16 differs from a dimension of the settingportion 22 in a region immediately adjacent to theanchoring feature 16 by at least 0.05 mm and preferably by at least 0.25 mm. - The
decorative element 12 is made from a material that can resist high temperatures. In particular, thedecorative element 12 is made from a material having a melting point that is higher, preferably at least 20 °C higher, than the melting point of the metal that is to form thebody 14 of thedecorative article 10. In this way, thedecorative element 12 can be set into thedecorative article 10 using a cast-in-place method, as will be later described. The material of thedecorative element 12 may therefore be selected to match the material of thebody 14, or vice versa. In one example, thedecorative element 12 is made from a material having a melting point that is higher than 1200°C. In this particular embodiment thedecorative element 12 is made from sintered zirconia, though thedecorative element 12 may be made from other materials, particularly other sintered materials, such as alumina, a spinel, or another suitable ceramic material. - When the
decorative element 12 is set in thearticle 10, as shown inFigure 2a , thebody 14 of thedecorative article 10 surrounds theentire setting portion 22 of thedecorative element 12. Thebody 14 includes four anchoring features 18, defined by recesses, which are filled by the fourlugs 16 of thedecorative element 12. In use, the co-engagement of therecesses 18 defining the anchoring features of thebody 14 and thelugs 16 defining the anchoring features of thedecorative element 12 prevents thedecorative element 12 from falling out of thebody 14 and sets it securely in place. -
Figures 3a and 3b show an alternative embodiment of thedecorative article 110, which is substantially the same as the decorative article ofFigures 1 ,2a and 2b , except for the form of the anchoring features. More specifically, in the embodiment ofFigures 3a and 3b , theanchoring feature 116 of the decorative element is defined by a recess provided in the settingportion 122, which is engaged with acorresponding protrusion 118 that defines the engagement feature in thebody 114 of the decorative article 110 (visible only inFigure 3a ). In this example, fourrecesses 116 are positioned on two opposite sides of the settingportion 122 of thedecorative element 110, with tworecesses 116 on each side to provide four anchoring points. - Each
recess 116 extends into themain setting portion 128 by a distance that is sufficient to hold theelement 112 securely in place in thearticle 110. To this end, in this example, therecess 116 has a depth of at least 0.05 mm. In this way, as with the embodiment ofFigures 2a and 2b , a dimension of the settingportion 122 in the region of theanchoring feature 116 differs from a dimension of the settingportion 122 in a region immediately adjacent to theanchoring feature 116 by at least 0.05 mm. - As with the embodiment shown in
Figures 2a and 2b , thebody 114 of thedecorative article 110 surrounds theentire setting portion 122 of thedecorative element 112, with four corresponding anchoring features 118 of thebody 114 in the form of protrusions extending into the fourrecesses 116 that define the anchoring features of thedecorative element 112. In use, the co-engagement of theprotrusions 118 that define the anchoring features of thebody 114 and therecesses 116 that define the anchoring features of thedecorative element 112 prevent thedecorative element 112 from falling out of thebody 114 and sets it in place. -
Figures 4a and 4b show yet another embodiment of thedecorative article 210, in which each anchoring feature 216 of thedecorative element 212 is defined by a recess in the form of an elongate groove that extends along a side of the settingportion 222 of thedecorative element 220. In this example, there are twoelongate grooves 216, positioned on opposite sides of the settingportion 222, such that thedecorative element 210 has two anchoring features 216. Thebody 214 of thedecorative article 210 again surrounds theentire setting portion 222, with two protruding anchoring features 218 of thebody 214 filling theelongate grooves 216 such that co-engagement of the grooves defining the anchoring features 216 of thedecorative element 212 and the protruding anchoring features 218 of thebody 214 sets thedecorative element 212 in place. -
Figures 5a and 5b show a further embodiment of thedecorative article 310, in which each anchoring feature 316 of thedecorative element 312 is defined by a protrusion in the form of an elongate ridge that extends along a side of the settingportion 322 of thedecorative element 312. In this example, there are twoelongate ridges 316, positioned on opposite sides of the settingportion 322, such that thedecorative element 312 has two anchoring features 316. Thebody 314 of thedecorative article 310 again surrounds theentire setting portion 322, with two anchoringfeatures 318, defined by elongate recesses in thebody 314, being filled by theelongate ridges 316 such that co-engagement of therecesses 318 defining the anchoring features of thebody 314 and theridges 316 defining the anchoring features of thedecorative element 312 sets thedecorative element 312 in place. -
Figures 6a and 6b show a still further embodiment of thedecorative article 410, in which theanchoring feature 416 of thedecorative element 412 is defined by a protrusion in the form of a rim that extends around the entirety of the settingportion 422. In this example, the rim is flared to define a sloping upward-facing surface (i.e. a sloping surface that faces generally in the same direction as thepresentation portion 420 of the decorative element 412). In this way, the settingportion 422 is widest nearest thebase 424, at the bottom of thedecorative element 412, and narrowest nearest thepresentation portion 420. However, it will be appreciated that other rim shapes may also be used, for example in which the rim is not flared, but defines a flat upward-facing surface. - When the
decorative element 412 is set into thearticle 410, thebody 414 of thedecorative article 410 again surrounds theentire setting portion 422, with ananchoring feature 418, defined by a correspondingly shaped recess inbody 414, engaging the flaredrim 416 of thedecorative element 412, such that thedecorative element 412 is set in place. -
Figures 7a and 7b show a yet further embodiment of thedecorative article 510, in which each anchoring feature 516 of thedecorative element 512 is defined by asloped protrusion 516 extending outwardly from the sides of themain setting portion 528 of thedecorative element 512. Eachsloped protrusion 516 has an upwardly-facing surface that slopes from the base 524 towards thepresentation portion 520 of thedecorative element 512. In this example, there are four anchoringfeatures 516 in total, positioned on two opposite sides of the settingportion 522, with two anchoring features 516 on each side. - When the
decorative element 512 is set into thearticle 510, thebody 514 of thedecorative article 510 again surrounds theentire setting portion 522, with four anchoringfeatures 516 of thebody 514, defined by correspondingly slopedrecesses 518, filled by the slopedprotrusions 516 of thedecorative element 512, such that co-engagement of the anchoring features 516 of thedecorative element 512 and the anchoring features 518 of thebody 514 sets thedecorative element 512 in place. - The
decorative elements Figure 2b will now be described with reference toFigure 8a . - As shown in
Figure 8a , themould assembly 40 comprises amould 42 and at least one former 44. Themould 42 comprises amould body 46 having amoulding surface 48 that surrounds aninterior moulding volume 50. Themoulding surface 48 defines apresentation surface 52 which will form the surface of thepresentation portion 20 of thedecorative element 12, and a settingsurface 54, which in combination with the former 44 will form the surface of the settingportion 22 of thedecorative element 12. - The
formers 44 are responsible for forming the anchoring features 16 of thedecorative element 12, and as such are a negative impression of thecorresponding anchoring feature 16. Theformers 44 are positioned such that they are located adjacent to the settingsurface 54 of themould 16, so as to form the anchoringformation 16 as part of the settingportion 22 of thedecorative element 12. - In this example, the
mould assembly 40 is for use in forming the decorative element ofFigure 2b and hence theformers 44 take the form of recesses in the settingsurface 54, to allow formation of protruding anchoring features 16 of thedecorative element 12 in the form of lugs. Therecesses 44 have a depth of at least 0.05 mm, to form a correspondingprotrusion 16 with a length of at least 0.05 mm. - In this example, the
formers 44 are integral with themould 42 to form aunified mould assembly 40. However, it should be understood that theformers 44 may not be integral withmould 46 and may be separate components to themould assembly 40. -
Figure 8b shows an alternative example of amould assembly 140 for making the decorative element ofFigure 3b , comprising amould 142, which again comprises amould body 146 having amoulding surface 148 surrounding aninterior moulding volume 150. Themoulding surface 148 defines apresentation surface 152 which will form the surface of thepresentation portion 120 of thedecorative element 112, and asetting surface 154, which together with the former 144 will form the settingportion 122 of thedecorative element 112. - The
mould assembly 140 additionally comprisesformers 144, located adjacent to thesetting surface 154 to form the anchoring features 116 of thedecorative element 112. - In this example, the
mould assembly 140 is for use in forming thedecorative element 112 ofFigure 3b , wherein the anchoring features 116 are recesses in the settingportion 122. As such, theformers 144 in this example are protrusions that are provided on thesetting surface 154 to protrude into themoulding volume 150. Theprotrusions 144 have a length of at least 0.05 mm, preferably at least 0.25 mm to form acorresponding recess 116 in thedecorative element 112 with a depth of at least 0.05 mm, preferably at least 0.25 mm. - As with the example shown in
Figure 4 , theformers 144 inFigure 5a are integral with settingsurface 154 of themould assembly 140. However, in other embodiments, theformers 144 may be provided as separate insert pieces that can be inserted into themould 142. - It will be appreciated that the configuration of the formers can be adapted as necessary so as to form differently shaped anchoring features, such as the anchoring features of the decorative elements of
Figures 4b ,5b ,6b and7b . Generally, the formers take the form of protrusions provided on, or recesses provided in, the setting surface of the mould, the protrusion or recess being any suitable shape or size. - A method of making the decorative elements using the mould assemblies described above, and a finished decorative article, will now be described, with particular reference to the decorative element of
Figure 2b , and the mould assembly ofFigure 8 . - In the first stage of production, an element-forming material that will form the
decorative element 12 is first provided, in the form of a feed stock. The element-forming material comprises a powder; in this example, the powder is powdered ZrO2 (zirconia), though it will be appreciated that other suitable powders may be used, such as other powdered ceramics, including powdered alumina (Al2O3) or powdered spinels, particularly transparent spinels. - The powdered zirconia is mixed with a binder, such as an organic binder, and optional additives such as pigments, to form the element-forming material. In this example, the resulting element-forming material has a paste-like consistency. The element-forming material is then poured into the
mould assembly 40 so as to fill themoulding volume 50. The element-forming material is packed against thepresentation surface 52 and settingsurface 54 of themould 42, and is also packed around and into the former 44, such that the element-forming material takes the desired form of thedecorative element 12, including theanchoring feature 16. - With the element-forming material in the
mould 42, a two-stage heat treatment is performed. - The heat treatment comprises an initial debinding step, which provides initial densification and drives off the binder. The debinding step comprises heating the element-forming material inside the mould to a temperature of between approximately 300 °C and 500 °C for a time of between approximately 1 hour and 10 hours to form a green body.
- The heat treatment additionally comprises a sintering step, in which densification is completed and a blank is formed. The sintering step comprises heating the green body to a temperature of between approximately 1000 °C and 1500 °C, preferably approximately 1200 °C for a time of between approximately 2 hours and 20 hours.
- The blank is then de-moulded, and finally, undergoes a surface finishing treatment to create the finished
decorative element 12. - By virtue of the former 44, the blank, and hence the final
decorative element 12, is formed with the anchoringfeature 16 moulded into the settingportion 22 of thedecorative element 12. In this way, the anchoringfeature 16 is a moulded feature. The anchoringfeature 16 is thereby formed as an inherent part of the process of making thedecorative element 12, without the need for a separate machining step to make theanchoring feature 16, which would otherwise be labour and cost intensive. In this way, adecorative element 12 with an anchoringfeature 16 can be made particularly quickly, efficiently and cost effectively. - It will be appreciated that materials used for cabochons are generally inexpensive compared to materials used for facet cut stones. Machining an anchoring feature is a comparatively expensive process, and thus would increase the cost of a cabochon significantly. As a result, cabochons are not typically used in invisible settings, as the cost of providing the required anchoring feature is prohibitive. By moulding the anchoring
feature 16 using the former 44 in the manner described above, the anchoringfeature 16 that is essential for providing an invisible setting can be formed in a cost-effective way in a relatively inexpensive cabochon element, thereby allowing a cabochon element to be used in an invisible setting without adding prohibitively to the cost of the article. - By virtue of the use of a powder processing method involving sintering, the
decorative element 12 is a sintered element, made of a material with a relatively high melting point. As a result of this high melting point, the cast-in-place method can be used to set the decorative element into a decorative article, as will now be described. - The
body 14 of thedecorative article 10 is typically made of a metallic material, such as silver, gold, bronze, copper, steel, aluminium, or another suitable casting metals or alloys. - To cast the
body 14 using a cast-in-place process, liquid wax is first injected into a rubber mould to form a wax model of thebody 14. Thedecorative element 12 is then positioned on the wax model as it would be in the finisheddecorative article 10. The wax model is then placed in a crucible and filled with investment, typically in the form of gypsum, which surrounds the wax model and thedecorative element 12. The crucible, containing the gypsum, wax model anddecorative element 12 is the heated in an oven, typically at a temperature between approximately 650°C and 750°C for a time of between approximately 1 and 3 hours to burn out the wax while leaving thedecorative element 12 in place. - The space left by the wax is filled by pouring in molten metal into the mould to surround the
decorative element 12 and form thebody 14. The crucible, now containing the gypsum, metal and thedecorative element 12, is then allowed to cool before being placed in water to dissolve the gypsum, leaving the now-solidified body around thedecorative element 12. Thebody 14 is polished and finished to leave the completeddecorative article 10. - It should be noted that the
decorative element 12 need not be made and set into thedecorative article 10 in the same manufacturing location. Instead, a first stage in which thedecorative element 12 is formed may take place in a first manufacturing location, and a second stage in which thebody 14 is cast around thedecorative element 12 to form thedecorative article 10 may take place in a second manufacturing location different to the first. - The cast-in-place method, made possible by the relatively high melting point of the
decorative element 12, allows a fast and cost-effective method of setting adecorative element 12 into an invisible setting. The cast-in-place method also provides a particularly secure setting of thedecorative element 12 in thedecorative article 10, providing a high-quality finished product that is resistant to normal wear. - It will be apparent to the skilled person that many variations of the above embodiments are possible without departing from the scope of the appended claims.
Claims (15)
- A method of making a decorative element for use in an invisible setting, the decorative element (12) comprising a presentation portion (20), a base (24) and a setting portion (22) extending between the presentation portion and the base, wherein the setting portion comprises an anchoring feature (16), the method comprising:
providing a mould arrangement comprising:a mould (42) comprising a presentation surface (52) for forming the presentation portion of the decorative element and a setting surface (54) for forming the setting portion of the decorative element; anda former (44) for forming the anchoring feature, the former being located adjacent to the setting surface;arranging an element-forming material into the mould to surround the former;performing a heat treatment to form a decorative element with an anchoring feature. - The method of Claim 1, wherein the element-forming material comprises a powder, which is optionally a ceramic powder, preferably zirconia (ZrO2), alumina (Al2O3) or a spinel and optionally wherein the element-forming material further comprises a binder, preferably an organic binder, and/or a pigment.
- The method of Claim 1 or Claim 2, wherein the heat treatment comprises a sintering step, which preferably comprises heating the decorative element to a temperature of between approximately 1000°C and approximately 1500°C, preferably approximately 1200°C for a time of between approximately 2 hours and approximately 20 hours.
- The method of Claim 3, wherein the heat treatment comprises a debinding step, which preferably comprises heating the decorative element to a temperature of between approximately 300°C and approximately 500°C for a time of between approximately 1 hour and approximately 10 hours.
- The method of any preceding claim, wherein the anchoring feature is an opening or recess in the setting portion and the former is arranged to protrude from the setting surface, or wherein the anchoring feature is a protrusion on the setting portion and the former is a recess in the setting surface.
- The method of any preceding claim, wherein the former is integral with the mould.
- The method of any preceding claim, wherein the setting portion defines the widest region of the decorative element.
- The method of Claim 7, wherein a dimension defined by the anchoring feature differs from a dimension of the remainder of the setting portion adjacent to the anchoring features by at least 0.05 mm, preferably at least 0.25 mm.
- The method of any preceding claim, wherein at least a portion of the presentation portion of the decorative element has a substantially curved surface, and/or wherein the base of the decorative element is substantially planar.
- The method of any preceding claim, wherein the decorative element is a cabochon.
- A method of making a decorative article (10), the decorative article comprising a body (14) and the decorative element (12) of any preceding claim set in the body with an invisible setting, the method comprising, casting the body around the decorative element to engage the body with the anchoring feature (16) of the decorative element to set the decorative element in place.
- The method of Claim 11 wherein the casting process is a cast-in-place process.
- A decorative element (12) for use in an invisible setting, the decorative element comprising a presentation portion (20), a base (24) and a setting portion (22) extending between the presentation portion and the base, wherein the setting portion comprises an anchoring feature (16), wherein the decorative element is a sintered element and wherein the anchoring feature is a moulded feature.
- A decorative article (10) comprising a body (14) and the decorative element (12) of Claim 13, or a decorative element made according to the method of any of Claims 1 to 10, wherein the body is engaged with the anchoring feature (16) of the decorative element to set the decorative element into the body in an invisible setting.
- The method of Claim 11 or Claim 12, or the decorative article of Claim 14, wherein the decorative article is an article of jewellery, a watch or a decorative household item.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP19167168.4A EP3718430B1 (en) | 2019-04-03 | 2019-04-03 | Decorative element for an invisible setting |
Applications Claiming Priority (1)
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EP19167168.4A EP3718430B1 (en) | 2019-04-03 | 2019-04-03 | Decorative element for an invisible setting |
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EP3718430A1 EP3718430A1 (en) | 2020-10-07 |
EP3718430B1 true EP3718430B1 (en) | 2023-07-05 |
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EP19167168.4A Active EP3718430B1 (en) | 2019-04-03 | 2019-04-03 | Decorative element for an invisible setting |
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USD968997S1 (en) | 2020-02-21 | 2022-11-08 | Venus by Maria Tash, Inc. | Earring |
USD973531S1 (en) | 2020-02-27 | 2022-12-27 | Venus by Maria Tash, Inc. | Earring |
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KR200183269Y1 (en) * | 1999-12-28 | 2000-05-15 | 배안식 | The grain for decoration of a ring consists of ceramic |
KR101307067B1 (en) * | 2010-11-09 | 2013-09-11 | 김택형 | Method for manufacturing a health bracelet |
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