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 ...

Figure 1. Sapphires from Madagascar: a beautiful 3.29 ct untreated faceted stone and an assortment of rough in the background. Madagascar has produced many high-quality stones in the last few years ...

Sri Lanka has two monsoon seasons that occur at different times of the year depending on the part of the country. The northeast has monsoons from December through March. In the southwest, where most ...

Filigree inlay art originated in the Warring States Period (475-221 BC). At the time, it was called “Jin Yin Cuo,” which involved painting gold and silver on the surface of bronze artworks. With the ...

Right now, we’re standing on the steep slopes of Donnelly Butte, just above the Ponderosa mine’s pit. At our backs, magnificent stands of lofty ponderosa pines extend uphill. We are about a five-hour ...

Figure 1. Spinel is available in a wide range of colors, as seen in this suite of round gems weighing 1.47–6.70 ct faceted by Bill Vance. Photo by Robert Weldon/GIA; courtesy of Vance Gems. Spinel has ...

This chart focuses primarily on the types of natural inclusions found in tourmaline, as well as the minerals in which tourmaline can be found as an inclusion. Treatments such as enhancement of ...

Jadeite jade is one of the most important aggregate gems in today’s global marketplace, with known sources in Myanmar, Japan, Russia, and Guatemala. Among them, Myanmar is the most legendary and still ...

Gain in-depth knowledge about the multitude of colored stones sold in today’s market. Topics include which gems are commercially important and why, the differences in gem values and shifting supply ...

The GIA Laboratory-Grown Diamond Quality Assessment provides an overall quality evaluation that classifies each laboratory-grown diamond as Premium or Standard. The diamond’s girdle is laser inscribed ...

Amethyst can be safely cleaned with warm soapy water. Ultrasonic cleaners are usually safe except in the rare instances where a stone is dyed or treated by fracture filling. Steam cleaning is not ...

GIA reports represent the highest standard of reliability, consistency and integrity. And now, GIA Report Check is available for all GIA reports, providing you with an additional level of assurance.