This 6.30-carat black boulder opal from Queensland, Australia, displays vivid play-of-color. Black opals are highly valued because their dark body tone showcases play-of-color more dramatically than ...

ABOUT GIA An independent nonprofit organization, GIA (Gemological Institute of America), established in 1931, is recognized as the world’s foremost authority in gemology. GIA invented the famous 4Cs ...

Once a gem is submitted: Your name or store info is removed, so analysis is completely unbiased. Every gem, whether from a local jeweler or a globally recognized brand, is evaluated using the same ...

The fee for the GIA Laboratory-Grown Diamond Quality Assessment is US$15 per carat, with a minimum fee of $15. Submissions that do not meet the minimum criteria for assessment will be charged a US$5 ...

The Motswedi diamond weighed 2,488.32 carats (approximately 1.10 pounds!) upon arrival at GIA, along with 11 smaller fragments that had broken off, weighing a total of 1.50 carats. Two larger pieces ...

Once a stone is submitted, client information is withheld from the non-client-facing staff who conduct the analysis. This measure helps ensure an unbiased report. Before undergoing examination, each ...

The primary chemical analysis methods applied in gemology are XRF, which uses X-ray emissions for nondestructive testing, and LA-ICP-MS, which provides detailed analysis and greater sensitivity.

Industry analysts project that by 2025, 20% of all diamonds on the market will be laboratory-grown. Indeed, the gem industry has seen a significant increase in the quantity, size, and quality of ...

At the earth’s surface, graphite is the stable crystalline form of carbon, with a density of 2.26 g/cm 3. Diamond is a much more compact form of carbon, with a density of 3.52 g/cm 3, 56% higher than ...

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 ...

Nathan Renfro, Tyler Smith, John I. Koivula, Shane F. McClure, and James E. Shigley ...

Manufacture of a solid single-crystal diamond ring is a very complex and challenging process. Once material is removed from the crystal, very fine fractures and imbalanced strain can have severe ...