Abstract:
A system includes a radiation source to provide short wavelength light. A holder positions a table of a gemstone to receive the light. A detector is positioned to receive fluorescent light from the gemstone when the gemstone is a CVD grown gemstone.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/463,106, filed May 8, 2009 which claims priority to U.S. Provisional Application Ser. No. 61/051,929, filed May 9, 2008, the entire disclosures of which are incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    Chemical vapor deposition grown diamonds can be difficult to distinguish from mined diamonds using conventional techniques. Detection of CVD diamond is of importance to the diamond industry to prevent the fraudulent sale of CVD diamond as natural diamond, and to enable the detection of CVD diamond for the purpose of ensuring that there is no misrepresenting natural as CVD diamond. Further, the detection of CVD diamond may be useful for protecting intellectual property rights. 
         [0003]    The detection of CVD diamond is difficult and laborious due to the fact that multiple instruments are needed. Such instruments are used to first determine that the diamond in question is a type II A. Colorless cvd diamonds currently are type II A which indicates a very low nitrogen level. The instruments are then used for testing for the presence of N-V centers, which are a substitutional nitrogen atom adjacent to a carbon vacancy. Finally, instruments are used to microscopically view diamonds for features such as strain. All of these tests are required to raise the certainty that a diamond is natural or cvd. None of these tests are complete in themselves, as the presence of N-V centers is rare in natural diamonds, but does occur. Such N-V centers fluoresce at red-orange wavelengths due to it&#39;s two main emission peaks centered at 575 and 637 nm. The purer the diamond the weaker the fluorescence. The fluorescence can also be seen by illuminating the diamond with short wavelength ultraviolet light in an expensive instrument such as the “Diamond View”. The detection process is long and difficult for large pure stones and nearly impossible for small stones. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a block diagram of a system for detecting CVD grown diamonds in a retail setting according to an example embodiment. 
           [0005]    FIG,  2  is a graph illustrating photo luminescence (PL) of white, brown and pink cvd diamonds. 
           [0006]      FIG. 3  is a block diagram of an alternative system for detecting CVD grown diamonds in a retail setting according to an example embodiment. 
           [0007]      FIG. 4  is a cross section representation of combined fibers according to an example embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims. 
         [0009]    A system  100  in  FIG. 1  may be used to detect CVD grown diamond. System  100  may be formed in a size that is compatible for deployment in a jewelry retail store and be operated by relatively unskilled personnel. System  100  may utilize the presence of an N-V center in a CVD grown diamond. At  110 , a radiation source provides short wavelength light. The short wavelength light may be provided by a green or blue laser, such as a commercially available semiconductor laser which emits at 405 or 532 nm. Many other wavelengths may be used that cause fluorescence of diamonds with N-V centers, such as wavelengths in the 400 to 550 nm range, and may include portions of the UV range of 10 to 400 nm., or at least the upper portions of the UV range. Other sources that provide suitable wavelength light may also be used. 
         [0010]    A fiber optic delivery system or lens  120  may be used to provide short wavelength radiation to a holder  125  to position a table of a gemstone  130  at a predetermined distance from the light. The holder  125  may be adapted with suitable fixtures such as clamps or platforms with indentations to hold a loose gemstone or gemstones, as well as a piece of jewelry containing one or more gemstones such as diamonds. The laser in one embodiment is highly focused on the crystal surface of the gemstone. A fitter(s) (or spectrometer)  140  may be used to separate the laser light from the PL light (photo-luminescence). 
         [0011]    The presence of N-V centers would result in emission bands centered at about 575 and/or 637 nm, and the filters can be used to allow detection of these wavelengths. A detector  150  may be positioned to receive and detect the PL light, in one embodiment, a thermoelectric cooler  160  may be used to cool the gemstone. The cooler  160  may be integrated with the holder  120  in one embodiment. Alternatively to a thermoelectric cooler, a cooling media such as liquid nitrogen or dry ice may be positioned proximate to the gemstone to cool the gemstone. 
         [0012]    Detector  150  may contain suitable electronics and metering to indicate the nature and type of the diamond from the detected PL light. Detector  150  may be used in conjunction with microscopic examination to confirm the natural or CVD origins of the gemstone. Further filtering of wavelengths may also be used to detect treated natural stones or high pressure high temperature created stones. In a further embodiment, handling of the stones may be automated so that they could be continuously measured and recorded without human handling. 
         [0013]    in further embodiments, filters or an inexpensive spectrometer may be used to separate wavelengths to ensure that the laser light and the PL light are separated. A suitable covering may be used to eliminate stray room light from entering the detector and laser light from straying to the outside. Safety interlocks may be provided to shut down the laser in the event the cover is removed. Holder  125  may be made large enough to hold several sizes of stones. Control circuitry and sensors may be included to indicate a pass, fail, or further inspection notice for the tester. 
         [0014]      FIG. 2  is a graph illustrating photo luminescence (PL) of white, brown and pink cvd diamonds. 
         [0015]    Some embodiments may be made fairly inexpensive and have a fairly small footprint, and may be easy to operate, making them suitable for use and operation by a store clerk in a retail store. 
         [0016]      FIG. 3  is an alternative system  300  may be used to detect CVD grown diamond. System  300  may be formed in a size that is compatible for deployment in a jewelry retail store and be operated by relatively unskilled personnel. System  300  may utilize the presence of an N-V center in a CVD grown diamond. At  310 , a light source provides short wavelength light to an optical fiber  315  that may be optimized to transmit the short wavelength light. The short wavelength light may be provided by a green or blue laser, such as a commercially available semiconductor laser which emits at 405 or 532 nm. Many other wavelengths may be used that cause fluorescence of diamonds with N-V centers, such as wavelengths in the 400 to 550 nm range, and may include portions of the UV range of 10 to 400 nm, or at least the upper portions of the UV range. Other sources that provide suitable wavelength light may also be used. 
         [0017]    The optical fiber  315  provides the light from light source  310  to a sample holder  320  to position a table of a gemstone at a predetermined distance from the light The sample holder  320  may be adapted with suitable fixtures such as clamps or platforms with indentations to hold a loose gemstone or gemstones, as well as a piece of jewelry containing one or more gemstones such as diamonds. The light from light source  310  in one embodiment is highly focused on the crystal surface of the gemstone. 
         [0018]    In one embodiment, CVD diamonds will fluoresce, producing a PL light. This produced light is returned back to the optical fiber  315 , which branches into a second type of fiber  325  optimized to transmit wavelengths corresponding to the PL light. 
         [0019]    The presence of N-V centers would result in emission bands centered at about 575 and/or 637 nm, and the second type of fiber  325  may be used to carry such emissions to a spectrometer  330  to perform detection of these wavelengths. The fibers  315  and  325  diverge at a junction  335  such that each may carry it corresponding light independently of the other. 
         [0020]    In one embodiment, a thermoelectric cooler may be used to cool the gemstone. The cooler may be integrated with the holder  320  in one embodiment. The spectrometer  330  may contain suitable electronics and metering to indicate the nature and type of the diamond from the detected PL light In some embodiments, the spectrometer  330  may be used in conjunction with microscopic examination to confirm the natural or CVD origins of the gemstone. Further filtering of wavelengths may also be used to detect treated natural stones or high pressure high temperature created stones. In a further embodiment, handling of the stones may be automated so that they could be continuously measured and recorded without human handling. 
         [0021]    In further embodiments, a light splitter may be used at  335  to separate wavelengths in fibers  315  and  325  to ensure that the light from light source  310  and the PL light from the diamond fluorescence are separated. In one embodiment, the components are mounted on a substrate, such as a board or other supportive material, and a suitable covering may be used to eliminate stray room light from entering the system, and keep laser light from straying to the outside. Safety interlocks may be provided to shut down the light source in the event the cover is removed. Holder  320  may be made large enough to hold several sizes of stones. Control circuitry and sensors may be included to indicate a pass, fail, or further inspection notice for the tester. 
         [0022]      FIG. 4  is a cross section representation of combined fibers  315  and  325  from  FIG. 3  represented generally at  400 . In one embodiment, fiber  315  is represented as a single fiber at  410 , surrounded by multiple fibers  325 , as represented with reference number  420 . This cross section illustrates the combined fibers taken along lines  4 - 4  in  FIG. 3 . The fibers are then separated at junction  335  to provide independent paths for the generated and emitted light. 
         [0023]    The Abstract is provided to comply with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.