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Two natural “horse conch” pearls and their shell.
Two Natural “Horse Conch” Pearls

Rare pearls, along with their shell, are studied in the Hong Kong lab.

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Sapphire cabochon displaying asterism.
Unique Star Sapphire with Transparent Core

A sapphire cabochon with an unusual appearance is seen at GIA’s Tokyo lab.

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The repaired diamond.
A Repaired Diamond

A marquise-cut diamond is found to have been broken and reassembled with an unknown adhesive.

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Natural inclusions are visible when the assemblage is viewed face-up.
Beryl and Glass Assemblage Imitating Emerald

An unusual assembled stone is examined at GIA’s New York lab.

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Irradiated CVD synthetic diamonds.
Three Irradiated CVD Synthetic Diamonds

Irradiated CVD-grown diamonds are examined in the Carlsbad lab.

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Chatoyancy on one side of green bead.
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.

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An exceptionally large and clean 1.91 ct faceted oval brilliant afghanite.
Large Faceted Afghanite

A report on the largest facet-grade afghanite seen in the GIA gem identification department.

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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

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

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Within a parcel of 1,102 diamond melee, 1,092 were identified as HPHT synthetics.
One Natural Melee Diamond Found in Large Batch of HPHT Synthetic Melee

A single natural diamond is found within the largest percentage of undisclosed synthetic melee submitted to GIA.

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This 15.32 ct cushion modified brilliant is the largest HPHT synthetic diamond graded by GIA.
15 Carat HPHT Synthetic Diamond

A synthetic diamond seen in the Carlsbad lab is the largest faceted lab-grown diamond examined by GIA.

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