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 ...

Large quantities of rubies—both rough and faceted—from a commercially important new source in Myanmar (Burma) have been available on the Bangkok market since 1992. The ruby crystals from the Mong Hsu ...

The September birthstone is sapphire – a gem that’s been cherished for thousands of years. Although the term sapphire usually refers to the blue variety of corundum (ruby is the red variety), this ...

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 ...

Reviews the advancements and major trends in laboratory-grown diamonds observed by GIA since 2007. Gemological and Trace Element Characteristics of Cassiterite from Yunling, China Examines gem-quality ...

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, ...

2020年10月、GIAは、新たにデザインされた合成（ラボラトリーグロウン）ダイヤモンド レポートを発表しました。新しいデジタル専用のフォーマットで提供されるこのレポートには、以前に ...

GIA IT will be performing maintenance on our internal systems from Friday, October 18th (5 PM PT) to Saturday, October 19th 2024 (8 PM PT). During this maintenance window, the My Lab application, ...

We grade only loose diamonds because a mounting or setting can obscure or influence the color and clarity grade and make it difficult to determine an exact carat weight. Grading loose stones also ...

Diamond is available in a range of sizes and qualities to fit every consumer's tastes. One of the first things most people learn about diamonds is that not all diamonds are created equal. In fact, ...

The 75.47-carat Hooker Emerald was worn by Ottoman Sultan Abdul Hamid II, the last sultan of the Ottoman Empire. Photo by Chip Clark, courtesy Smithsonian Institution, National Museum of Natural ...

To address concerns about laboratory-grown and treated diamonds being mixed into parcels of melee, GIA has developed an automated system to analyze and sort melee-size diamonds quickly and accurately.