红宝石是刚玉矿物种别（其中还包括蓝宝石）中的一个类别。 红宝石备受珍视，每克拉单价很高。可以说，红宝石是有色宝石市场中最重要的宝石之一。 最纯的刚玉矿物是无色的。微量元素 ...

Commercial quantities of gem-quality chrysoprase and green prase opal (nickel-bearing chalcedony and common opal, respectively) have been recovered from altered serpentinite deposits near Haneti, ...

Commercial quantities of gem-quality benitoite are known from a single location in the world, the Benitoite Gem mine in the New Idria district of San Benito County, California. A barium titanium ...

Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. (The exception to this is fancy color diamonds, ...

The GIA Laboratory-Grown Diamond Report includes full quality assessment with a plotted clarity diagram. Color and clarity specification are described on the same scale as the GIA Diamond Grading ...

During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges. This transformation was caused by the ...

Those born in January are lucky to have the beautiful and diverse garnet as their birthstone. Garnets are commonly red but also come in an extraordinary range of beautiful colors, including orange, ...

This large Australian light opal cabochon weighs 117.85 carats. Small play-of-color flashes of orange and green predominate in a pinfire pattern, with spots of a more muted blue over a grayish ...

As a consumer, you will regularly encounter in the marketplace gems that have been treated to change their appearance. A topic that often comes up is whether a particular gemstone is or isn’t treated.

Observations of Oval-, Pear-, and Marquise-Shaped Diamonds: Implications for Fancy Cut Grading Presents findings from observations of oval-, pear-, and marquise-shaped diamonds, laying the groundwork ...

"The Path of Enlightenment" necklace contains 180 magnificent opals from Lightning Ridge, Australia, a famous opal producing area. - Courtesy Cody Opal Opal is the product of seasonal rains that ...

GIA is the world’s most trusted name in diamond grading and gem identification. With objectivity and expertise as its hallmarks, GIA ensures the integrity and accuracy of every report it issues. GIA ...