Large HPHT-Treated Blue Type IIb Diamond
Properties of, and theories on colour zoning exhibited by, the largest HPHT-treated blue diamond graded by GIA.
Yellow HPHT-Processed Rough Diamond
HPHT annealing of a nearly eye-clean yellow natural rough diamond is revealed through spectroscopic analysis.
Treated Pink Type IIa Diamond Coloured by Red Luminescence
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.
Treated Pink Diamond with HPHT Synthetic Growth Structure
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
Blisters examined in the Bangkok lab have been treated with an artificial filler.
LPHT-Annealed Pink CVD Synthetic Diamonds
The New York lab examines three pink CVD synthetic diamonds which have received LPHT annealing treatment.
Hydrophane Opal Treatment
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
A synthetic spinel has undergone quench-cracking treatment, possibly to make it appear a natural specimen.
Fluorite Sphere with Phosphorescent Coating
A sphere with unusual phosphorescence is seen in the Carlsbad laboratory.
Very Large Artificially Irradiated Yellow Diamond
Examination of a 59.88 ct irradiated yellow diamond, one of the largest irradiated diamonds identified by GIA.