John Chapman (“Gemetrix”, Australia)
- Date: February 25, 2021
- Length: 1h 31m
Optical instruments are at the heart of a gemmologist’s or gem lab’s tool kit. For diamonds, the main ones are based on fluorescence, PL (Raman) spectroscopy, and absorption spectroscopy – from UV to IR. These methods can detect defects in diamonds that correspond to the history of a diamond. Understanding the principles of the instruments and their application to diamonds aids in determining the origin (natural or synthetic) of a diamond and whether any colour treatments have been applied. How the instruments work and are used in practice, their strengths and limitations will be presented in a webinar.
John Chapman has a degree in physics and has been active in the diamond industry for over 30 years mostly working for Rio Tinto Diamonds in a technical capacity. Since leaving the company he has been director of Gemetrix Pty which has developed and currently manufactures luminescence-based instruments to detect synthetic and treated diamonds and gems. More recently the company has developed a compact system for both PL and visible absorption spectroscopy. He is chief editor for the Mediterranean Gem and Jewellery Conferences and editor of Branko Deljanin’s 2021 book “DIAMONDS: Natural, Treated and Laboratory-grown”.