Commercial quantities of gem-quality chrysoprase and green prase opal (nickel-bearing chalcedony and common opal, respectively) have been recovered from altered serpentinite deposits near Haneti, ...

Commercial quantities of gem-quality benitoite are known from a single location in the world, the Benitoite Gem mine in the New Idria district of San Benito County, California. A barium titanium ...

The GIA Laboratory-Grown Diamond Report includes full quality assessment with a plotted clarity diagram. Color and clarity specification are described on the same scale as the GIA Diamond Grading ...

Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. (The exception to this is fancy color diamonds, ...

Although various forms of paints and coatings intended to alter the color of diamond have likely been in use for almost as long as diamonds have been valued as gems, the modern era of diamond ...

During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges. This transformation was caused by the ...

The GIA Cultured Pearl Classification Report is an abbreviated report that provides classification information on unmodified cultured pearls. This dossier-sized report includes a detailed ...

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 ...

A new production of hydrothermal synthetic emeralds, grown in the Czech Republic with Italian technology, has been marketed since December 2004 with the trade name Malossi synthetic emerald. Several ...

Adjacent amethyst and citrine colors in the same crystal of quartz have been reported from South America, although there appears to be uncertainty as to the exact locality of origin. Such material has ...

The best ametrines show distinct areas of orangy yellow and purple. These colors are featured in this graceful cut design. Photo by Lydia Dyer, © John Dyer & Co ...

The red variety of the mineral tugtupite, a rare silicate closely related to sodalite, has been used as a gemstone since 1965. This article presents the history of the mineral and details of its ...