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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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Article
GIA Gem Project
Various Gems
(Amblygonite - Axinite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Corundum

Ruby and sapphire (usually blue, but also in every other color) have been the most important colored gemstones for several thousand years. Originating historically in southeast and central Asia, and more recently in eastern Africa, these colored varieties of the mineral corundum have been much sought as gems because of their rarity, color and durability. Gem corundum can display asterism and chatoyancy due to the presence of oriented mineral inclusions, and in some cases, a change of color when viewed under different light sources.

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Article
GIA Gem Project
Various Gems (Olivine - Rutile)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Various Gems
(Sapphirine - Stibiotantalite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Various Gems (Taaffeite - Zoisite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Various Gems
(Danburite – Humite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Various Gems (Barite - Cuprite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Tourmaline

Tourmalines have a very complex chemical composition, and more than a dozen mineral species are recognized within this group.

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Article
GIA Gem Project
Various Gems
(Kornerupine - Natrolite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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