Metrology, the science of measurement and its application, plays a critical role in the accuracy of GIA’s research and laboratory services. The metrology team closely monitors the performance of ...

Figure 1. This gold ring with a phoenix motif features a Neyshabur turquoise (13 × 17 mm), with a 0.02 ct ruby on each side and diamond accents. Courtesy of Taktala Jewelry, Tehran. Turquoise is an ...

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 ...

Carved single-crystal diamond rings are rare, with few examples to reference (see Spring 2020 Lab Notes, pp. 132–133). But with advancing technology in the laboratory-grown diamond industry, the ...

Although today’s global freshwater cultured pearl market is mostly dominated by Chinese products, Japanese freshwater pearl cultivation started in 1935. Lake Biwa in Shiga Prefecture supplied pearls ...

Diamonds are the most amazing of gems. Just as amazing, however, is how natural diamonds reach Earth’s surface. Diamonds are formed 150 to 700 km deep in Earth, and are then carried upward in a rare ...

Two specimens of faceted crystalized carbon - both are crystal clear and give off a kaleidoscope of spectral colors in direct light. They appear to be identical. One, however, is a billion or more ...

Originally published in GemGuide in 2016, this comprehensive series examines the quality factors that influence the value of colored gemstones, with a specific emphasis on the role cut quality plays ...

Of all the sapphire deposits found in Montana, the richest is in the Rock Creek (Gem Mountain) district. Between 1890 and the 1930s, over 65 tonnes of rough sapphire were recovered from this area and ...

Gem-quality synthetic or laboratory-grown diamonds are more available in today’s jewelry marketplace than ever before, causing both interest and concern about lab-grown diamonds and whether ...

The Imperial Flame, a superb natural color Brazilian topaz, was fashioned from a 615 ct crystal recovered over 20 years ago. The finished piece measures 89.53 × 20.56 × 19.15 mm and weighs 332.24 ct.

GIA’s Diamond Cut Grading system for round brilliant diamonds includes seven components: brightness, fire, scintillation, weight ratio, durability, polish and symmetry. Fire is well illustrated in ...