UV-VIS-NIR Spectrometer

Allows the study of a continuous absorption spectrum between 200 and 2500 nm. Results obtained with a UV-VIS-NIR-spectrometer are

  • colour authenticity of diamonds (in connection with FTIR spectroscopy)
     
  • authenticity of emeralds
  • origin indications of sapphires
     
  • colour authenticity of black pearls

The two UV-VIS-NIR-spectrometers seen here are:

  • One VARIAN CARY 500 SCAN
    SPECTROPHOTOMETER, wavelength range between
    175 and 3300 nm. It can be used in
    transmitted mode as well as with an integration sphere for reflexion measurements.
  • One Hitachi U-4001 Spectrophotometer, spectral range between 250 and 2500 nm. This instrument is mainly used for coloured stones and pearls, where resolution is not as critical as in diamonds.

X-ray fluorescence spectrometry

Tracor X-ray spectrate 5000 Principle: X-rays excite the sample under analysis to fluoresce. The fluorescence lines in the spectrum show which chemical elements are present. Energy-dispersive X-ray fluorescence is used for routine analysis of chemical elements of all gemstones submitted for gemstone reports.
The chemical composition of a certain gemstone gives information about its authenticity, its origin, etc. The chemical composition of pearls indicates whether they are freshwater or saltwater pearls.

A Tracor X-ray spectrace 5000 energy-dispersive X-ray fluorescence spectrometer with Spectrace software can routinely be used for

  • identification and authenticity determination of all gemstones
     
  • origin determination of rubies, sapphires, emeralds, and alexandrites
     
  • determination of saltwater/freshwater pearls
     
  • determination of Ag-treatment of black pearls

Raman micro-spectrometry

Raman spectroscopy is a non-destructive micro method which is able to analyse only a small part of the gemstone which has been preselected before with an optical microscope. This way, inclusions in gemstones, fissure treatments etc. can be analysed. The Raman spectrometer is also used to identify gemstones set in jewellery, rough gemstones, or colour treatments of pearls.

At the right  is  a Renishaw Raman System 1000 with a laser excitation source at 514 nm and Galactic GRAMS/32 software is used for:

  • filler identification in emeralds (see also Publications)
  • gemstone identification - inclusion (solid and fluid) analysis
  • diamond research

De Beers Diamond View™

Another state-of-the-art instrument for diamond identification. De Beers supplies the Diamond View™, together with the DiamondSure™, and was developed at De Beers DTC Research Centre, Maidenhead, to distinguish synthetic diamonds from natural diamonds. The DiamondView™ produces a fluorescence image of the surface of a polished diamond, from which the growth structure of the stone may be determined. On the basis of this fluorescence pattern - which is quite different for natural as compared to synthetic diamonds - a positive identification of the nature of the diamond is assured.