WO2011101724A2

WO2011101724A2 - Gemstone administration and identification

Info

Publication number: WO2011101724A2
Application number: PCT/IB2011/000293
Authority: WO
Inventors: Ricardo Baretzky
Original assignee: Ricardo Baretzky
Priority date: 2010-02-16
Filing date: 2011-02-16
Publication date: 2011-08-25
Also published as: WO2011101724A3

Abstract

A certificate of authenticity of a unique gemstone is provided that carries physical details of the general shape, size and configuration of the gemstone. The certificate includes data developed spectroscopically as regards impurities contained within the gemstone and any other necessary properties thereof whereby the gemstone can be uniquely identified. The spectroscopically developed data may include a sequence trace showing the absorption frequencies pertinent to the particular gemstone and may be produced using a Fourier transform infrared (FTIR) spectroscope spanning a frequency or wave number range appropriate to the type of gemstone. The certificate may includes a UV-VIS record. The invention also provides a gemstone administration system wherein spectroscopically developed data generated in relation to each individual gemstone is such that it uniquely identifies that gemstone in amongst others and the spectroscopically developed data, together with other physical data the relevant gemstone, is maintained in a database for future use and reference.

Description

GEMSTONE ADMINISTRATION AND IDENTIFICATION

FIELD OF THE INVENTION

This invention relates to gemstone administration and identification, particularly in relation to diamonds but that can also be employed for certain other types of gemstones that have suitable atomic arrangements within a crystalline structure that enables a unique arrangement of a basic component and impurities to be suitably identified by spectroscopic means.

Whilst this patent application will be directed primarily to diamonds it will be understood by those skilled in the art that some of the principles will apply to other gemstones that are amenable to the same type of identification and such applications are intended to fall within the scope hereof. The term "gemstone" is thus to be interpreted in this specification as including gemstones other than diamonds that are susceptible to the administration and identification principles and criteria herein explained. The administration and identification provided by this invention is applicable to polished gemstones as well as the rough crystal form know as unpolished gems or diamonds. Applicant believes that the term "fingerprinting" or "fingerprint" is an appropriate appellation for the unique identification of gemstones in terms hereof

BACKGROUND TO THE INVENTION

Diamond type is a method of scientifically classifying diamonds by their level and type of chemical impurities. Diamonds are generally separated into four basic types according to the amount and type of impurities that are measured at the atomic level within the crystal lattice of carbon atoms and thus, unlike inclusions, require spectroscopic means, typically an infrared spectrometer, in order to detect them. The basic diamond types are Type la, Type lb, Type lla, and Type lib.

Type la diamonds are reported to make up about 98% of all natural diamonds. In these diamonds nitrogen impurities of up to about 0.1% are clustered within the carbon lattice, and are relatively widespread. The absorption spectrum of the nitrogen clusters can cause such diamonds to absorb blue light, making them appear pale yellow. If the nitrogen atoms are in pairs they do not affect the diamond's color then they are of Type laA. If the nitrogen atoms are in large even-numbered aggregates they impart a yellow to brown tint and are of Type laB.

Type lb diamonds are reported to make up about 0.1% of all natural diamonds. They contain similar amounts of nitrogen to Type la, but the impurities are more diffuse and dispersed throughout the crystal in isolated sites (not paired or grouped). These diamonds absorb green light in addition to blue, and have a more intense or darker yellow or brown colour than Type la diamonds. Synthetic diamonds that contain nitrogen are typically of Type lb.

Type lla diamonds are reported to make up 1-2% of all natural diamonds. These diamonds are almost or entirely devoid of impurities including nitrogen, and consequently are usually colourless. Occasionally, while Type lla diamonds are being extruded towards the surface of the Earth, the pressure and tension can cause plastic deformation whereby the tetrahedral structure becomes slightly misaligned, leading to imperfections. These imperfections can confer a yellow, brown, orange, pink, red, or purple colour to the gem.

Type Mb diamonds are reported to make up about 0.1 % of all natural diamonds. In addition to having extremely low levels of nitrogen impurities comparable to Type lla diamonds, Type lib diamonds contain significant boron impurities. The absorption spectrum of boron causes these gems to absorb red, orange, and yellow light, lending Type Mb diamonds a blue or grey colour, though examples with low levels of boron impurities can also be colourless.

Type II diamonds absorb in a different region of the infrared spectrum, and transmit in the ultraviolet below 225 nm, unlike Type I diamonds. They also have differing fluorescence characteristics, but no discernible visible absorption spectrum.

The enormous value of good quality diamonds has resulted in various activities aimed at artificially enhancing the value of diamonds of lesser value.

One of these activities is irradiation using proton and deuteron bombardment via cyclotrons; gamma ray bombardment via exposure to cobalt-60; neutron bombardment via the piles of nuclear reactors; and electron bombardment via Van de Graaff generators; the latter two being the most common. The high-energy particles physically alter the diamond's crystal lattice, knocking carbon atoms out of place and producing color centers. Irradiated diamonds are generally some shade of green, black, or blue after treatment, and most of them are annealed at elavated temperature to further modify their color into shades of yellow, orange, brown, or pink. The final color is dependent on the diamond's composition and the temperature and length of the annealing process. Such a diamonds retained residual radiation.

It is to be noted that some natural diamonds originating in particular areas and possess natural radioactivity and this can be distinguished from the artificial radioactivity residual from artificial irradiation. Another activity is high pressure high temperature treatment of otherwise gem-quality stones that may possess a brown color to lighten that color significantly, or remove it altogether. Diamonds treated to render them colorless are typically Type a and their color is attributable to structural defects that arose during crystal growth, generally known as plastic deformations, rather than to interstitial nitrogen impurities as is the case in most diamonds having a brown color. Type la diamonds, which have nitrogen impurities present in clusters that do not normally affect body color, can also have their color altered by high pressure high temperature treatment.

Some synthetic diamonds have also been given high pressure high temperature treatment to alter their optical properties and thus make them more difficult to differentiate from natural diamonds. Pressures of up to 70,000 atmospheres and temperatures of up to 2,000 °C (3,632°F) are used in such procedures.

Definitive identification of high pressure high temperature treated stones is carried out using Fourier transform spectroscopy (FTIR) and Raman spectroscopy to analyze the visible and infrared absorption of suspect diamonds and detect characteristic absorption lines indicative of exposure to high temperatures. Diamonds treated to remove their color by the company General Electric were given laser inscriptions on their girdles to help identify a treated diamond. It is, however, possible to polish this inscription away, so its absence cannot be used as a trusted sign of natural color. Although it is permanent, high pressure high temperature treatment should be disclosed to the buyer at the time of sale.

Modification of naturally occurring diamonds also takes place by laser drilling in order to remove defects followed by filling with particular types of glass that preferably have the same or a similar refractive index to that of diamond; filling defects that are available from the surface of a diamond with such a glass; and coating diamonds in order to generally enhance their color.

The value of diamonds is further abused in the so-called blood diamond or conflict diamond trade in which the sale of diamonds, often artificially modified natural diamonds or diamonds originating in a particular region especially a region with which naturally occurring radioactivity is associated, is used in order to raise funds for an insurgency, warlord's activities or terrorism.

Many of the diamonds that have been modified or that originate in areas in which they are introduced into the market by commercial routes that are not generally accepted or regarded as legal, become merged with the commercial traffic of legal diamonds in various different ways.

Present certification of diamonds does not adequately identify the diamond itself, or some of its properties, and the existing commercial system lays itself open to the substitution of one diamond for another having the same general description. It also facilitates the dishonest sale of modified diamonds as genuine naturally occurring diamonds.

This failing of the present system therefore leads to various dishonest and fraudulent practices in which the customer is generally the ultimate loser, typically not being sufficiently equipped with knowledge or equipment to detect that a diamond is not what it is purported to be.

It is estimated that a considerable amount of money changes hands in consequence of dishonest and fraudulent sales and that even governments lose considerable income that would be available by way of duties and taxes if the sale of all diamonds were conducted honestly and above board.

OBJECT OF THE INVENTION

It is one object of this invention to provide for enhanced certification of gemstones, and especially diamonds. It is another object of the invention to provide an administration system for gemstones, and especially diamonds, at least of preselected values or types, wherein certification of individual gemstones is carried out and records maintained of selected gemstones. It is a further object of the invention to provide the facility for creating a federal central database for the purpose, inter alia, of policing of fraudulent activities or for inventory control, or both.

SUMMARY OF THE INVENTION In accordance with a first aspect of this invention there is provided a certificate of authenticity of a unique gemstone carrying physical details of the general shape, size and configuration of the gemstone, the certificate being characterized in that it includes data developed spectroscopically as regards impurities contained within the gemstone and optionally other properties thereof whereby the gemstone can be uniquely identified.

Further features of the invention provide for the spectroscopically developed data to be a sequence trace showing the absorption frequencies pertinent to the particular gemstone; for the spectroscopically developed data to be produced using a Fourier transform infrared (FTIR) spectroscope spanning a frequency or wave number range appropriate to the type of gemstone; for the data to include a UV-VIS record; and for the balance of the data reflected on the certificate to be all or part of that customarily included in such certificates of authenticity.

Of course, the certificate may assume a hard copy format as is traditional in the relevant commercial arena, but it may also, either alternatively or in addition, be maintained in electronic format. In the instance of a diamond, the frequency range corresponds to at least the wave numbers from 3000 to 1000 cm^"1, and preferably from at least 4000 to a number in the range of 1000 - 600 cm^"1. A more extended range of from up to 10,000 to say 5000 cm^"1 can be employed in order to demonstrate that a diamond is, or is not, an irradiated diamond that would typically have a peak at about 1000 to 1 170 cm^"1 and/or 3200 to 2800 range of cm^"1 and also that a diamond is, or is not, one that has been heat treated at a high temperature and pressure that would typically result in an absorption band at about 1344 cm^"1.

Of course, nitrogen impurities would reflect as absorption bands at variable places such as 1361 cm^"1 in some instances, depending on circumstances, possibly 3107 cm^"1 , and boron impurities would reflect as absorption bands at about 1450 to 1451 .73 and/or 3107 cm^"1. The spectroscopically developed data such as FTIR data exhibit different distinguishable characteristic patterns for different types of diamond. Synthetically produced carbon based diamonds would show an absorption band at about 1344 cm^"1.

In the instance of other gemstones more restricted ranges of wave numbers may be sufficient and it is envisaged that a range of about 7000 cm^"1 to about 200 cm^"1 may be appropriate for natural emeralds; and from about 4000 cm^"1 , to about 400 cm^"1 , or less, may be appropriate for gemstones such as ruby and green garnet demantoid. The preferred methodology uses from 7000 cm^"1 to about 200 cm^"1 for all gemstones and semi-precious gems or minerals.

In accordance with a second aspect of the invention, there is provided an administration system for gemstones wherein individual gemstones are subjected to spectroscopic examination and the spectroscopically developed data generated in relation to each individual gemstone is such that it uniquely identifies that gemstone in amongst others, and wherein that spectroscopically developed data, together with other physical data the relevant gemstone, is maintained in a database for future use and reference. Further features of this aspect of the invention provide for spectroscopically developed data to be maintained in a central global database especially with a view to the prevention of fraudulent activities and terrorist activities; for the data recorded in the data base to include all data reflected upon the certificate defined above as well as information identifying the lawful owner, dealer, tradesman, government, or mine, of the relevant gemstone as well as any recorded transactions in that gemstone that are submitted to the administration system from time to time; for the FTIR (spectroscopically) developed data to be the same as is recorded on a relevant certificate as defined above; and for each new set of spectroscopically developed data relating to a gemstone submitted for spectroscopic examination in terms of the administration system to have its spectroscopic data added to those already recorded in the system database for the purpose of maintaining an ongoing mean set of spectroscopic data against which a new set of spectroscopic data can be compared, typically electronically, for conformity with general required features that certify that the gemstone is a gemstone of the type that it purports to be or simply that it is of a particular type.

In accordance with a third aspect of the invention there is provided equipment for generating a certificate as defined above, the equipment comprising a suitable spectrometer, a suitable crystallographic analyzer; computer means for correlating outputs from both relating to the same gemstone, and printer means for printing said certificate. The equipment may also include a calibrated UV-VIS measurement machine.

The equipment may be built into one integral unit that optionally includes a printer so that a self-contained machine is provided for producing certificates as defined above directly from a gemstone examined by the machine. Such a combined machine is intended to fall within the scope of this invention. In order that the above and other features of the invention may be more fully understood an expanded description thereof follows with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is an illustration of one form of certificate produced in terms of the invention;

Figure 2 is an example of a spectral trace produced using FTIR spectroscopy and illustrating a typical trace for a particular gem diamond having predominantly nitrogen impurities;

Figure 3 is a similar trace for a particular gem diamond having boron impurities;

Figure 4 is a similar trace for a synthetically produced carbon base diamond;

Figure 5 is a similar trace for an irradiated diamond;

Figure 6 illustrates a similar trace for a diamond shown together with a mean trace for the corresponding relevant type diamond;

Figure 7 is a block diagram of equipment used to produce a certificate as illustrated in Figure 1 ; Figure 8 is a schematic illustration showing the light path employed in one variety of tests; Figure 9 is a schematic demonstration showing the light path employed in two other varieties of tests; and,

Figure 10 shows the traces of 5 different diamond types in order to demonstrate their common features.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the first aspect of the invention that is illustrated in Figure 1 , a certificate of authenticity [1] of a unique gemstone carries physical details of the general shape, size and configuration of the gemstone, as indicated by numeral [2], as well as information indicated by numeral [3] corresponding to various preset attributes indicated by numeral [4]. The certificate also carries a UV-VIS record indicated by numeral [5]. This information is presently generally included in certificates of authenticity by means of a organic fingerprint. .

However, as provided by this invention, the certificate also has printed thereon data developed spectroscopically that indicates impurities contained within the diamond, this data being, in this instance, in the form of a Fourier transform infrared (FTIR) spectroscopic trace [6] spanning a frequency / wave number range appropriate to the type of diamond. In the present example, the diamond is a natural diamond and an appropriate frequency range was considered to correspond to the range of wave numbers 4000 cm^" ¹ to 200 cm^"1 (other ranges from 7000 to 200 have shown too much noise to conclusively study the diamonds).

The spectroscopically developed data, being a sequence trace showing the absorption frequencies / wave numbers pertinent to the particular gemstone, reveals various peaks that correspond to unique characteristics of the diamond and, indeed, each diamond or other gemstone has its own unique sequence trace that may be regarded as a fingerprint of the particular gemstone.

In the event that nitrogen is present as an impurity, a situation most common in the diamond trade, the presence of nitrogen is reflected by a peak [10] at a wave number of about 1361.98 cm^"1, as shown in Figure 2. In the instance of man-made diamonds, such nitrogen bands are absent, as in the case of natural type 1 diamond but is evidenced by detection from the 1400 to 1100 regions as in the case of type 2a diamond.

In the event that boron is present as an impurity, a situation much less common in the diamond trade, its presence would be reflected by a peak [11] at a wave number of about 3107 and 1450.49-1451.73 cm^"1 as shown in Figure 3.

The FTIR trace thus reveals definite distinguishable characteristic patterns for different types of diamonds such as laA-B,1Aa,1b, Ma and lib. This is reflected particularly by the impurities of the boron and nitrogen inside the diamond. These features are evidenced in absorption of mid or near infrared ranges. If the nitrogen bands or peaks are 10-5 ppm below then the diamond is considered type 2 consequent on the FTIR classification. In addition, the absence of such nitrogen is noted whereas the diamond is classified as a type 2a or 2b. Synthetic diamonds, that is to say man-made diamonds, show characteristic peaks [12] at the frequencies/wave numbers 1344 cm^"1 and / or 1332, as shown in Figure 4.

Irradiated diamonds, on the other hand, show a characteristic peak at 1000- 1100 cm^"1, as indicated by numeral [13] in Figure 5. These irradiated traces were found to be absent (that is less than 10ppm) in diamond potentially from Zimbabwe and conflict areas. However the peaks leaves of 4941 and 5164-5165 might be absent in natural irradiated diamonds whereas the peak would be present in artificially irradiated diamond. The latter will of course change colour in the diamond for example from brown to green. Irradiated diamonds also show strong peak levels at the 741 UV-VIS range during UV-Vis testing. Additional radiation can be detected at 4940-4941 and 5 64-5165 cm^"1. A more extended range of from up to 10,000 cm^"1 to say 5000 cm^"1 may be employed in order to demonstrate that a diamond is, or is not, an irradiated diamond that would typically also have absorption bands at about 4940-4941 and 5164-5165 cm^"1. However radiation characteristics of diamond found near conflict areas have shown an additional trace peak at 3106.80 cm^"1. It appears that a horn-like spike appears in conflict diamond from range 3237.32 to 3106.80 cm^"1. This could indicate the active natural radiation produced from the uranium deposits in the earth. This makes it very easy to distinguish a diamond from possible conflict origin since most diamonds from conflict areas are exposed to some form of natural radiation.

It is also possible to determine that a diamond is, or is not, one that has been created by CVD or HPHT methods (a high temperature and pressure) that would typically result in an absorption band at about 1344 cm^"1 (this mostly results in a total absorbtion band from 1344 to 200 cm^"1 range. Heat treatments may be revealled in two places, namely the 1000-400cm^"1 and 4500 to 7000 ranges.

In the instance of other gemstones a more restricted range of wave numbers may be sufficient and it is envisaged that a range of about 7000 to about 400 may be appropriate for natural emeralds; and from about 4000 to about 1600, or less, may be appropriate for gemstones such as ruby and green garnet demantoid. This range of wave numbers of 7000 to 400 is considered to be 1

13 sufficient for all gem types as a whole and different data is generated to enlarge the data and fingerprint of such a gem.

Turning now to the second aspect of the invention, and with reference to Figure 7 of the drawings, an administration system is provided for gemstones wherein individual gemstones are subjected to spectroscopic examination and the spectroscopically developed data generated in relation to each individual gemstone is such that it uniquely identifies that gemstone in amongst others. In addition it can also identify the organic substance as authentic of such a gem matched against the mean fingerprint generated from accumulated data entered. For example, by using a rough specimen, a data module can be built to generate this mean finger print that can instantly identify the gem as authentic or synthetic. The relevant spectroscopically developed data, together with other physical data relating to the relevant gemstone, is preferably maintained in a central global database [15] for future use and for reference purposes. This data base preferably includes all data reflected upon the certificate described above as well as information identifying the lawful owner of the relevant gemstone and any recorded transactions in that gemstone that are submitted to the administration system from time to time.

Each new set of spectroscopically developed data relating to a gemstone that is new to the administration system and that is submitted for spectroscopic examination in terms of the administration system, has its spectroscopic data added to that already recorded in the system for the purpose of maintaining an ongoing mean set of spectroscopic data for each type of gemstone against which the new set of spectroscopic data can be compared, generally electronically, for conformity with features that certify that the gemstone is of a particular type. W

It is to be mentioned that the spectroscope [16] used in the tests conducted to date is a Perkin Elmer Spectrum one FTIR machine with an assure ID analyzer and fitted with a support accessory for items such as gemstones. A beam condenser is used to focus the radiation for purposes of introducing it 5 to a gemstone such as a diamond by way of the pavilion and it is to be noted that the gemstone being examined needs to be orientated appropriately on the support accessory.

The geometry of the beams used for producing the relevant data are shown 10 clearly in Figures 8 and 9 of the drawings. Figure 8 illustrates a diamond [40] supported upside down on a support surface [41] and the relevant beam [42] his passed through the girdle of a diamond. Figure 9 illustrates simultaneously two instances in which a beam is passed through the diamond [45] that is supported on its table on a support surface in the form of 15 a mirror [46] with the beam passing and generally normally into the pavilion of the diamond to reflect in the mirror and be directed outwards. Mirrors [47] are used to direct the beam and, in the one instance, the mirrors are off-axis paraboloid reflectors and in the other instance they are planar mirrors. 0 The spectroscopic data detected by the spectroscope is fed to a computer

[17], that may not be embodied in the same machine or may a separate computer, and the data is processed using an algorithm based on soft independent modeling by class analogy (SIMCA) in order to provide a mean trace for that particular type of gemstone. Future gemstones submitted to the 5 system can then be measured against this mean spectroscopic data. Such a comparison is typically carried out electronically with the new data being added to the existing data in the data base and forming part of the basis on which a future mean trace is generated. Figure 6 illustrates a mean trace [18] outputted by such an algorithm and a new trace [19] that is compared with

30 the mean trace electronically. The fact that all different types of diamonds contain common features in their spectroscopic data is illustrated clearly in Figure 10. In that Figure there are superimposed the FTIR spectral trace of a type 1 aA diamond indicated by numeral [30]; one of a type 1 aA/B diamond indicated by numeral [31]; one of a type 1 b diamond indicated by numeral [32]; one of a type 2a diamond indicated by numeral [33]; and one of a type 2b diamond indicated by numeral [34]. Certain common features of the various types of diamonds are quite clear. One of these is a distinctive fingerprinting of all diamonds at a wave number of 1 170.52.

Simply for the sake of record, a Perkin Elmer Lambda 35 UV-VIS [20] was used to create the relevant UV-VIS data for inclusion on the certificate and the physical characteristics of the gemstone were measured using an OGI Mega-fire optical measurement machine [21 ].

As provided by the third aspect of the invention, equipment for generating a certificate is as described above, and includes a printer [22] for creating a hard copy of the certificate. Obviously an electronic record of each certificate is also maintained on the data base.

Numerous variations to what is described above are possible within the scope of the invention that is limited only to the provision of the inclusion on a certificate of authenticity of a particular gemstone of spectroscopically generated data that is unique to that particular gemstone. The information contained in the certificate therefore uniquely links the particular gemstone with the certificate and by regenerating the spectroscopically generated data from a gemstone, its genuineness can be checked against the certificate.

It is therefore possible that other forms of spectroscopic data will be suitable provided that they enable the gemstone to be uniquely identified in amongst other similar gemstones. It is to be noted that the data methodology above can be collected by any FTIR calibrated between 7000 and 200 provided that it can collect a clear interpretable collection of the data from each particular specimen.

Claims

CLAIMS:

1. A certificate of authenticity of a unique gemstone carrying physical details of the general shape, size and configuration of the gemstone, the certificate being characterized in that it includes data developed spectroscopicaliy as regards impurities contained within the gemstone and any other necessary properties thereof whereby the gemstone can be uniquely identified.

A certificate of authenticity as claimed in claim 1 in which the spectroscopicaliy developed data includes a sequence trace showing the absorption frequencies pertinent to the particular gemstone.

A certificate of authenticity as claimed in either one of claims 1 or 2 in which the spectroscopicaliy developed data is produced using a Fourier transform infrared (FTIR) spectroscope spanning a frequency or wave number range appropriate to the type of gemstone.

A certificate of authenticity as claimed in any one of the preceding claims in which the data includes a UV-VIS record.

5. A certificate of authenticity as claimed in any one of the preceding claims in which the certificate has a hard copy format or electronic format, or both.

6. A certificate of authenticity as claimed in any one of the preceding claims in which the gemstone is a diamond and a scanned frequency range corresponds to at least the wave numbers from 3000 to 1000 cm^"1.

7. A certificate of authenticity as claimed in claim 6 in which the scanned frequency range includes at least 4000 to a number in the range of 1000 - 600 cm^-1.

A certificate of authenticity as claimed in claim 7 in which the scanned frequency range extends from 10,000 to 5000 cm^"1.

An administration system for gemstones wherein individual gemstones are subjected to spectroscopic examination and the spectroscopically developed data generated in relation to each individual gemstone is such that it uniquely identifies that gemstone in amongst others, and wherein that spectroscopically developed data, together with other physical data the relevant gemstone, is maintained in a database for future use and reference.

An administration system as claimed in claim 9 in which the spectroscopically developed data is maintained in a central global database.

An administration system as claimed in either one of claims 9 or 10 in which the data recorded in the data base includes all data reflected upon the certificate as claimed in any one of claims 1 to 9 as well as information identifying the lawful owner, dealer, tradesman, government, or mine, of the relevant gemstone.

An administration system as claimed in any one of claims 9 to 11 in which the data includes any recorded transactions in that gemstone that are submitted to the administration system from time to time. 13. Equipment for generating a certificate as defined in any one of claims 1 to 8 comprising a suitable spectrometer, a suitable crystallographic analyzer; computer means for correlating outputs from both relating to the same gemstone, and printer means for printing said certificate.

Equipment as claimed in claim 13 in which the equipment includes a calibrated UV-VIS measurement machine.