Research Article Search Results

This article discusses the history and ongoing development of GIA's color grading system, and explains how its laboratory applies it.

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania.

The finest and rarest emeralds are sometimes said to have an optical effect called gota de aceite.

High-quality CVD-grown diamonds, comparable in color and clarity to natural diamonds, can be identified using a combination of gemological and spectroscopic properties.

This article reviews the GIA Laboratory’s history of reporting on certain types of graining which are often the only characteristics present in large, high-clarity, high-color diamonds.

In early 2004, the GAAJ laboratory in Japan issued a lab alert about rubies they had seen that had large numbers of fractures filled with high-lead-content glass, which made them appear very transparent.

A new chart, supplementing the one published in the Winter 1995 issue of Gems & Gemology, summarizes the features of both as-grown (“non-modified”) and treated (“modified”) synthetic diamonds currently in the gem market (that is, those grown by the high pressure/high temperature technique).

The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish, and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.

For more than a century, the Four Peaks mine in Maricopa County, Arizona, has produced gem-quality amethyst from crystal-lined or crystal-filled cavities and fractures in a brecciated quartzite host rock.

This article compares some of Chatham Created Gems’ synthetic colored diamonds to natural diamonds and explains the results.

In recent years, the obligation to fully disclose all gem treatments has changed from a mere ethical responsibility to a legal one.

Just because you don’t see it, doesn’t mean it isn’t there. Many areas in the jewelry industry—education, gemological research, lecturing, publication, and laboratory and inventory documentation, to name a few—either require or benefit from high-quality photomicrography.