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Suite containing over 36 carats of Yogo sapphire
Gemological Characterization of Sapphires from Yogo Gulch, Montana

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

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Kasumigaura pearl necklace and recently harvested nucleated pearls
Cultured Pearls from Lake Kasumigaura: Production and Gemological Characteristics

Examines Japanese “Kasumiga” freshwater cultured pearls, which grow in a variety of colors.

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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

Analyzes the chemical composition and inclusion characteristics of this ancient artifact.

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Paula Crevoshay’s “Yogo Columbine” sapphire pendant
The Role of Silicon in the Color of Gem Corundum

Considers the previously unreported but critical impact of silicon on the coloration of gem-quality sapphire.

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Non-nacreous Pen Pearls
Observations on Pearls Reportedly from the Pinnidae Family (Pen Pearls)

Examines the internal structure, chemical composition, and spectroscopic features of 22 pen pearls.

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Nephrite Jade from Val Malenco, Italy: Review and Update

Analysis of 21 rough and gem-quality samples offers an update on the composition and properties of this pale green gem from the Italian Alps.

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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 superdeep environment.

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Dalmatian stone samples
True Colors of “Dalmatian Jasper”

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

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A blue synthetic star sapphire from past production of Wiede’s Carbidwerk
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany

Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s through the 1970s.

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