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 ...

Practice the same time-tested procedures and identification skills used by the Institute’s renowned gemological experts. Tools used include a microscope, a refractometer with polarizing filter and a ...

GIA programs and courses are offered year-round on a rolling basis at GIA campuses around the globe. This enables students to jumpstart their gem and jewelry career studies at the soonest, most ...

この75.47カラットのHooker（フッカー）エメラルドは、オスマン帝国最後のスルタンであったアブドゥル·ハミド2世が着用したもの。 - Chip Clark、提供：Smithsonian Institution, National Museum of Natural History ...

Diamond color is usually the result of selective absorption of incident white light. The unabsorbed portion of this light is transmitted through the diamond and is interpreted by the human vision ...

Figure 1. The bright red faceted ruby in this gold ring is from the large and potentially productive Snezhnoe deposit in Tajikistan. Photo by Zamoniddin Z. Nasriddinov. Discovered during the late ...

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.

Jadeite is 6.5 to 7, and nephrite is 6 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 ...

Diamond “type” is a concept that is frequently mentioned in the gemological literature, but its relevance to the practicing gemologist is rarely discussed. Diamonds are broadly divided into two types ...

Gemological and spectroscopic properties of CVD synthetic diamonds from Gemesis Corp. were examined. Their color (colorless, near-colorless, and faint, ranging from F to L) and clarity (typically VVS) ...