At the GJX and Pueblo shows, Nomad’s (New York City) had high-quality heliodor and topaz that were carefully cut to retain the beautiful rough etching patterns characteristic of this material (figure ...

A chemical and spectroscopic comparison of two purple gem spinel samples, one of them the first reported example of a spinel with a saturated purple color caused predominantly by chromium and cobalt.

Cuprian (copper-bearing) tourmaline, known as “Paraíba” tourmaline in the trade, has been an important gem since its discovery in 1989. Until now, almost all of the material reported has been ...

Investigates the morphological changes of macle diamonds during the growth process by exploring their three-dimensional internal zonal structure.

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 ...

GIAは、Gübelin宝石コレクションの中から400以上の重要な宝石を研究しており、この宝石学的情報の宝庫を共有することに全力を尽くします。この研究は、すべての学生、宝石鑑別士、研究員 ...

Two pearls presented a unique challenge, as testing at three different gemological laboratories could not conclusively identify them as natural or cultured, determine a freshwater or saltwater growth ...

Courtesy of Tom Dodge CollectionThis 54.32-carat fire obsidian displays vibrant colors caused by thin-film interference. Light reflects off nanoscale layers of magnetite within the stone, and the ...

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 ...

Fluorescence and phosphorescence can assist in revealing whether a gemstone is natural, laboratory-grown or treated. GIA developed this guide so retailers can use fluorescence tests to help identify ...

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 ...