Over the last two decades, knowledge of the formation of gem deposits has improved significantly. This article reviews the state of our knowledge of the geology and genesis of gem corundum and emerald ...

Basic, intermediate, and alkaline igneous rocks can sometimes also display similar pegmatitic textures. They include pegmatitic gabbro, syenite, and nepheline syenite, all of which are composed of ...

Photoluminescence imaging, which analyzes how gemstones glow under ultraviolet light, is an important analytical tool for detecting impurities, natural versus synthetic gems, and treatments through ...

Learn about the differences – and similarities – between natural and laboratory-grown diamonds, and how GIA’s researchers and grading laboratories can tell the difference ...

Nature gives us a brilliant palette of color-changing leaves and a spectacular kaleidoscope of sunsets during the fall season. Yet, year-round, a treasure trove of gemstones in rich earth tones is ...

Presents findings from observations of oval-, pear-, and marquise-shaped diamonds, laying the groundwork for a fancy cut grading system.

Fortunately, the identification of faceted moldavite is simple. Besides their flow texture and abundant bubbles (almost always much more abundant than in an artificial glass), moldavites contain ...

Opal is considered an October birthstone. Some people think it’s unlucky for anyone born in another month to wear an opal. But that particular superstition comes from a novel written in the 1800s ( ...

Every GIA diamond grading report contains an assessment of a diamond’s polish and symmetry, which are contributing factors in determining the overall quality of a diamond’s finish. This guide explains ...

Search GIA's library catalog of 65,000 books, 230,000 images, 2200 videos, 1200 periodicals, and the renowned Cartier Rare Book Repository and Archive.

The quarterly journal of the Gemological Institute of America.

Search GIA's library catalog of 65,000 books, 230,000 images, 2200 videos, 1200 periodicals, and the renowned Cartier Rare Book Repository and Archive.