Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds
A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.
The “Type” Classification System of Diamonds and Its Importance in Gemmology
Knowledge of type allows gemmologists to better evaluate if a diamond might be treated or synthetic, and whether it should be sent to a laboratory for testing.
GE POL Diamonds: Before and After
This article explores and identifies the changes that type IIa GE POL diamonds experience before and after HPHT annealing.
A History of Diamond Treatments
Modern gemmologists and diamantaires are faced with a broad spectrum of colour and clarity treatments ranging from the simple to the highly sophisticated.
Synthetic Moissanite: A New Diamond Substitute
Synthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation; this article reports on how to identify and characterise it.
A New Lasering Technique for Diamond
Several diamonds were treated for the purposes of observation and report with a new laser technique which does not show the typical surface-reaching drill hole.
“Fluorescence Cage”: Visual Identification of HPHT-Treated Type I Diamonds
HPHT-treated type I diamonds of various colours may exhibit unusually intense fluorescence at the facet edges and junctions.
Spectroscopic Evidence of GE POL HPHT-Treated Natural Type IIA Diamonds
Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.
A Chart for the Separation of Natural and Synthetic Diamonds
Exploration of a chart designed to give jewellers and gemmologists a practical guide to identifying synthetic diamonds as they enter the jewellery trade.
Clues to the Process Used by General Electric to Enhance the GE POL Diamonds
General Electric has developed a variety of high-temperature annealing techniques at different pressures for enhancing the optical properties of polycrystalline synthetic diamond films and single-crystal synthetic diamond.