15 Carat HPHT Synthetic Diamond
A synthetic diamond seen in the Carlsbad lab is the largest faceted lab-grown diamond examined by GIA.
Beryl and Glass Assemblage Imitating Emerald
An unusual assembled stone is examined at GIA’s New York lab.
Cabochons Fashioned from the Shell of Crassostrea Virginica
Crassostrea virginica, the so-called Eastern or American oyster, is a commercial seafood widely distributed along the east coast of the United States to the Gulf of Mexico.
HPHT合成メレーの大きなバッチで発見された1つの天然メレーダイヤモンド (英語)
Over the last decade, the production methods used to create synthetic diamond melee have improved substantially, along with the quality of the specimens themselves.
Three Irradiated CVD Synthetic Diamonds
Irradiated CVD-grown diamonds are examined in the Carlsbad lab.
Two Natural “Horse Conch” Pearls
Rare pearls, along with their shell, are studied in the Hong Kong lab.
Unique Star Sapphire with Transparent Core
A sapphire cabochon with an unusual appearance is seen at GIA’s Tokyo lab.
Large HPHT-Treated Blue Type IIb Diamond
A look at the color zoning exhibited by the largest HPHT-treated blue diamond graded by GIA.
Large Pinkish Orange CVD Synthetic Diamond
A combination of size, color, and clarity made this the most remarkable CVD synthetic diamond GIA has tested so far.
A Cat’s-Eye Rock Consisting of Jadeite and Amphibole
Raman spectroscopy reveals that a green bead, showing chatoyancy on one side, comprises jadeite and amphibole.
Large Faceted Afghanite
A report on the largest facet-grade afghanite seen in the GIA gem identification department.
A Repaired Diamond
A marquise-cut diamond is found to have been broken and reassembled with an unknown adhesive.