Commonly seen in HPHT-grown synthetic diamonds with a green component, nickel-related defects were identified for the first time in a type Ia natural diamond with a strong green component.

Farmers have experimented with bead nucleation, but until recently the methods tried did not produce the quantity or quality necessary for economic success.

Historically, global rough diamond production has fluctuated greatly due to a myriad of causes, many of which are explored in this article.

Numerous natural-color colored diamonds from the Aurora Butterfly of Peace and other collections were studied using a new type of fluorescence spectrometer.

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.

Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) is an important technique for quantitative chemical analysis.

Zircon inclusions in sapphires from Madagascar were studied to investigate the effects of heat treatment on their gemological and spectroscopic features.

Eight decades after the Cullinan diamond was mined, a team of gemologists examined the two famous gems that were created from it to become part of the Crown Jewels of England.

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.

Treated cultured pearls with a “chocolate” coloration have entered the market from several sources.

Political upheavals and technological advances, as well as changes in social and governmental attitudes and initiatives, have produced major and ongoing changes in the diamond industry.

Solid, vapor, and fluid inclusions in transparent gem rhodonite crystals from Broken Hill, New South Wales, Australia, have been identified for the first time using Raman spectroscopy and gemological/petrographic techniques.

Zambia is considered the world’s second most important source of emeralds by value (after Colombia).

The Mt. Mica area in southwestern Maine has been mined for tourmaline and other pegmatite gems since the 1820s.

Chameleon diamonds are among the rarest of gem diamonds.

Using a multi-step process, Lucent Diamonds has developed a new treatment process for certain natural diamonds that creates colors from pink-purple through red to orangy brown.

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).

Peridot: The ultimate value of a gemstone suite lies not only in the cost and quality of the materials themselves, but also in the selection of the rough, the quality of the faceting, and the intricacy of the setting in a well-designed and well-manufactured suite of jewelry.

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.

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.