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HPHT-treated blue diamond (left) with ragged-looking graphitization around an inclusion (center) and high-order interference colors with crossed-polarizing filters (right).

Large HPHT-Treated Blue Type IIb Diamond

Evan M. Smith, Paul Johnson, and Kyaw Soe Moe, August 9, 2018

Properties of, and theories on colour zoning exhibited by, the largest HPHT-treated blue diamond graded by GIA.

Yellow HPHT-Processed Rough Diamond

Sally Chan, November 23, 2015

HPHT annealing of a nearly eye-clean yellow natural rough diamond is revealed through spectroscopic analysis.

4.29 ct color-treated Fancy brown-pink diamond

Treated Pink Type IIa Diamond Coloured by Red Luminescence

Sally Eaton-Magaña, November 7, 2016

A type IIa colour-treated diamond was graded as Fancy brown-pink under daylight conditions and Fancy purplish grey under incandescent lighting, a colour change that resulted from HPHT annealing and irradiation.

Natural Fancy pink diamond with apparent HPHT synthetic growth structure.

Treated Pink Diamond with HPHT Synthetic Growth Structure

Kyaw Soe Moe and Wuyi Wang, February 1, 2016

A Fancy pink type IIa diamond showing cuboctahedral growth and greenish blue phosphorescence is shown to be a natural, treated coloured diamond.

Natural Blisters with Partially Filled Areas

Areeya Manustrong, August 3, 2016

Blisters examined in the Bangkok lab have been treated with an artificial filler.

LPHT-annealed CVD synthetics with their DiamondView images

LPHT-Annealed Pink CVD Synthetic Diamonds

Kyaw Soe Moe, Ulrika D’Haenens-Johansson, and Wuyi Wang, July 31, 2015

The New York lab examines three pink CVD synthetic diamonds which have received LPHT annealing treatment.

Opal slices before and after water immersion

Hydrophane Opal Treatment

Ratima Suthiyuth and Vararut Weeramonkhonlert, April 28, 2016

An opal rough is immersed in water and treated with oil and Opticon to observe effects on transparency and play-of-colour.

Quench-Crackled Blue Synthetic Spinel

Sudarat Saeseaw and Charuwan Khowpong, April 28, 2016

A synthetic spinel has undergone quench-cracking treatment, possibly to make it appear a natural specimen.

Fluorite Sphere with Phosphorescent Coating

Nathan Renfro, July 31, 2015

A sphere with unusual phosphorescence is seen in the Carlsbad laboratory.

59.88 ct Fancy Vivid yellow irradiated diamond

Very Large Artificially Irradiated Yellow Diamond

Christopher Vendrell and Paul Johnson, November 7, 2016

Examination of a 59.88 ct irradiated yellow diamond, one of the largest irradiated diamonds identified by GIA.

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