Figure 1. This alexandrite cabochon appears brownish green in fluorescent light (left) and brownish purple in incandescent light (right). The cabochon shows chatoyancy under both forms of illumination ...

GIA’s laboratories use advanced instrumentation and research to deliver accurate grading, identification, and origin ...

Cultured pearls come in different sizes, shapes, and colors. Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most ...

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, ...

大多数日光石体色呈黄色、橙色或褐色。 体色呈绿色的日光石极为罕见。 体积较小的内含物导致日光石在其体色之外泛出红色或金色；而体积较大的内含物则形成富有吸引力的闪烁反光。 日光石内含物可以是赤铁矿、铜或一些其它矿物。 俄勒冈州日光石是一种 ...

Birthstones are a fun, popular and colorful introduction to the world of gemstones. They appeal to audiences around the world regardless of gender, age, nationality or religion. Birthstones carry ...

Opal can range from 5 to 6.5 on the Mohs hardness scale. Hardness and toughness Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with ...

Fine-color, large, and eye-clean (lacking visible inclusions) rubies like this 11.01carat (ct) stone from Myanmar (formerly known as Burma) are extremely rare and valuable. – Photo: Robert Weldon/GIA.

This 7.19-carat alexandrite was cut to feature its beautiful color change. When the light source changes from daylight to incandescent light, the gem’s color changes from bluish green to reddish ...

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 ...

Emerald, the birthstone for May, has been beloved for millennia, evoking rebirth and renewal. Widely regarded as the definition of green, emerald is the perfect color for spring. From the poetic ...

Jadeite comes in a wide range of colors. The most valuable is an intense green called Imperial. - Courtesy Mason-Kay Fine Jade Jewelry To understand the value of jade, you have to look beyond its ...