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A Sunstone Odyssey, Part 1: The Ponderosa

The first of a three-part series exploring Oregon’s state gem reports on a July 2013 visit to the Ponderosa mine, a prolific sunstone source surrounded by majestic ponderosas.

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Rough blue spinel crystals from Luc Yen
Blue Spinel from the Luc Yen District of Vietnam

Offers geological context and gemological characterization of this increasingly popular vivid blue spinel from northeast Vietnam.

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Peridot from Sardinia, Italy
Characterization of Peridot from Sardinia, Italy

Gem-quality peridot is occasionally found as mantle xenoliths within basalts near Pozzomaggiore.

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 Hand holding tube-shaped boulder opal
Article
Queensland Opal Fields: Home of the Unique Australian Boulder Opal

Boulder opal is becoming more and more popular. Australia’s central Queensland is the home of more than a dozen of sources of this stone. Come with GIA field gemologists to find out more about this unique gem.

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An early black and white photo that shows deep trenches dug into the ground in the search for diamonds. Ladders and ropes help the miners excavate and traverse the mine.
Article
Historical Reading: The Diamond Fields of South Africa: Part 1 (1868-1893)

The discovery of diamonds in South Africa in early 1867 marked the start of an historic period of diamond exploration.

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Miners use shovels and sluicing equipment to search for diamonds near the Vaal River in South Africa.
Article
Historical Reading List: The Diamond Fields of South Africa: Part 2 (1893-2014)

Within a few years of their discovery, the diamonds deposits of South Africa produced more diamonds than what had come from India in two millennia.

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Santa Terezinha De Goias Emeralds
The Santa Terezinha De Goias Emerald Deposit

Brazil has become a leading producer of emeralds; this article examines one of the most significant deposits.

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Sapphires from Australia

An overview of Australia's recent significance in the production of blue sapphire.

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The Yogo Sapphire Deposit
The Yogo Sapphire Deposit

Yogo Gulch, discovered more than 100 years ago, is one of four major sapphire-producing areas in Montana, United States.

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Diamond from Jericho eclogite and Juina superdeep diamond
Diamonds from the Deep: How Do Diamonds Form in the Deep Earth?

G&G’s newest section explores how diamonds form in the deep earth.

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