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Eight natural-color pistachio pearls
Identification of “Pistachio” Coloured Pearls Treated by Ballerina Pearl Co.

A report on the colour treatment process for these intensely greenish yellow to yellowish-green cultured pearls and the techniques for identifying them.

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Two variscite cabochons from central Tajikistan
Variscite from Central Tajikistan: Preliminary Results

A look at the gemmological properties and chemical composition of this light blue to light green to green gem material, which is suitable for cabochon cutting.

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A piece of diamond rough with green body color and triangular etchings on the surface.
Article
GIA Researchers Reveal the Secrets of Diamond-in-a-Diamond Mystery

GIA researchers in New York recently had the opportunity to examine one of the most interesting and unique diamond crystals ever found.

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A face-up view of a cushion cut diamond with blue color.
Article
Gems & Gemology’s 7 Most Unusual Encounters from 2019

Check out some of the most interesting and unusual diamonds and coloured stones submitted to GIA’s laboratories in 2019.

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A woman sits in front of a computer screen with the DiamondView to her right.
Article
Inside De Beers’ Lightbox Diamonds

GIA researcher analyses and confirms that De Beers’ Lightbox diamonds are grown using the chemical vapour deposition process.

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Suite containing over 36 carats of Yogo sapphire
Gemmological Characterisation of Sapphires from Yogo Gulch, Montana

A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire.

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Timeline showing the use of garnets in different eras from 300 BCE to 700 CE
An Early Byzantine Engraved Almandine from the Garibpet Deposit, Telangana State, India: Evidence for Garnet Trade Along the Ancient Maritime Silk Road

Analyses the chemical composition and inclusion characteristics of this ancient artefact.

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Accurate Reporting of Key Trace Elements in Ruby and Sapphire Using Matrix-Matched Standards

Presents a group of corundum standards developed by GIA to improve the accuracy and efficiency of its laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) instruments.

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Rough CLIPPIR diamonds
The Very Deep Origin of the World’s Biggest Diamonds

Explores an exceptional family of diamonds, referred to as “CLIPPIR” (Cullinan-like, Large, Inclusion-Poor, Pure, Irregular and Resorbed), that formed in a super-deep environment.

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Dalmatian stone samples
True Colours of “Dalmatian Jasper”

Discusses the mineralogical composition and provenance of this spotted decorative gemstone.

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