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CVD, HPHT and Natural Diamonds
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Is There a Difference Between Natural and Laboratory-Grown Diamonds?

Learn about the differences – and similarities – between natural and laboratory-grown diamonds, and how GIA’s researchers and grading laboratories can tell the difference

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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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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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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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Fancy Dark brown to Fancy black Marange diamonds
Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions

Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.

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Recently discovered and legendary diamonds in the blue/gray/violet color range
Natural-Colour Blue, Grey and Violet Diamonds: Allure of the Deep

Summarises data collected on more than 15,000 natural blue/grey/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this colour range.

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Quartzite dyed to resemble ruby-in-zoisite.
Dyed Quartzite Imitation of Ruby-in-Zoisite

Beads appearing to be ruby-in-zoisite are revealed to be dyed quartzite.

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Micro-Features of Ruby
Inclusions in Natural, Synthetic and Treated Ruby

Provides a visual guide to the internal features of natural, synthetic and treated rubies.

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Three cultured pearls, one natural
Real-Time Microradiography of Pearls: A Comparison Between Detectors

Compares the image quality provided by real-time microradiographic imaging (RTX) units fitted with two different detectors: an image intensifier (II) and a flat panel detector (FPD).

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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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