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5.03 ct Fancy Deep Blue HPHT Synthetic Diamond
Largest Blue HPHT Synthetic Diamond

Analysis of a 5.03 ct HPHT-grown blue synthetic diamond, the largest ever examined by GIA.

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Turquoise with Fingerprint Pattern

A fingerprint pattern, possibly left by human skin oils during the assembly process, is observed in natural turquoise beads.

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A Useful Technique to Confirm the Hydrophane Nature of Opal

Observing a water drop’s interaction with opal, as well as refractive index, can confirm a specimen’s hydrophane nature with less risk of breakage than total immersion.

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Diamond with Unusual Laser Manufacturing Remnant

An unusual laser manufacturing remnant, possibly once used to guide a gem cutter, was left behind in a clock-like shape.

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Atypical Freshwater Cultured Pearls with Damaged Nacre

The New York lab received four baroque-shaped pearls with damaged nacre layers

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151451
Calcium Fluoride Coating Found on 13 "Fancy" Pink Diamonds

Recent lab examination reveals that traditional treatments such as calcium fluoride coating are still prevalent in the trade, and great care must be taken to identify them.

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151459
Very Large Rough Diamond

A report on a 1,138 ct rough diamond, possibly the largest ever examined by GIA.

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Confusing, Triangular Inclusions in an Art Deco-Style Pin
Spring 1991 G&G Lab Notes

This section, from the Spring 1991 issue of Gems & Gemmology, is a compilation of interesting finds from GIA’s laboratories.

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