Stuart Overlin, Brooke Goedert and Kellie Giordano, December 13, 2019
Check out some of the most interesting and unusual diamonds and coloured stones submitted to GIA’s laboratories in 2019.
Read MoreChristopher M. Breeding and James E. Shigley, June 1, 2009
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.
Read MoreThomas W. Overton and James E. Shigley, March 1, 2008
Modern gemmologists and diamantaires are faced with a broad spectrum of colour and clarity treatments ranging from the simple to the highly sophisticated.
Read MoreChristopher P. Smith, George Bosshart, September 1, 2000
This article explores and identifies the changes that type IIa GE POL diamonds experience before and after HPHT annealing.
Read MoreShane McClure, John M. King, June 1, 2000
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.
Read MoreDavid Fisher and Raymond A. Spits, March 1, 2000
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.
Read MoreKarl Schmetzer, December 1, 1999
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.
Read MoreKurt Nassau, Shane F. McClure, December 1, 1997
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.
Read MoreJames E. Shigley, Emmanuel Fritsch, December 1, 1995
Exploration of a chart designed to give jewellers and gemmologists a practical guide to identifying synthetic diamonds as they enter the jewellery trade.
Read MoreRobert C. Kammerling, Shane F. McClure, September 1, 1994
This report focuses on recent products from Yehuda/Diascience, Koss & Schecter Diamonds (Genesis II) and Clarity Enhanced Diamond House (a subsidiary of Goldman Oved Diamond Co.).
Read MoreYou are being redirected to GIA Alumni Association, LLC.