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.
Evidence of Focused Beam Irradiation in Treated Pink Diamond
DiamondView imaging and photoluminescence spectroscopy offered evidence of focused beam irradiation in a pink diamond.
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.
Very Large Artificially Irradiated Yellow Diamond
Examination of a 59.88 ct irradiated yellow diamond, one of the largest irradiated diamonds identified by GIA.
Unique Drilled Emerald
An emerald with drill holes containing a resinous material is seen in the New York lab.
Natural Blisters with Partially Filled Areas
Blisters examined in the Bangkok lab have been treated with an artificial filler.
Quench-Crackled Blue Synthetic Spinel
A synthetic spinel has undergone quench-cracking treatment, possibly to make it appear a natural specimen.
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.
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.
Yellow HPHT-Processed Rough Diamond
HPHT annealing of a nearly eye-clean yellow natural rough diamond is revealed through spectroscopic analysis.