Figure 1. Left: 18K yellow gold “Flames” ring with 25.19 ct Mexican fire opal. Right: This 18K yellow gold “Spice” ring ...

CARLSBAD, Calif. – November 4, 2024 – The GIA laboratory in Ramat Gan, Israel, will end operations by the end of 2024 due to changes in the global diamond industry that resulted in significant ...

Diamonds have a long history as a premier gemstone—a natural consequence of their beauty, rarity, and superlative physical properties such as extreme hardness. Diamonds that are mined for use as ...

The micro-world of gems lies at the very core of gemology. Information gathered from observations through the microscope serves as the very foundation for many conclusions drawn on a specimen, ...

A crystal and cut stone of Imperial Topaz from the Vermelhão mine near Ouro Preto in Minas Gerais, Brazil. Photo by Robert Weldon, courtesy of Bill Larson and Edward ...

Figure 1. Corundum is an example of a negative uniaxial mineral. This ruby crystal in matrix from Mogok, Myanmar, is approximately 6.15 cm in length. The cut gem is a 3.22 ct unheated ruby, also from ...

Earth’s surface is divided into tectonic plates, and the ones that make up the ocean floor are destined to sink. Sheets of oceanic crust typically bend and sink down into Earth’s interior at so-called ...

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 ...

Figure 1. Five loose “Edison” Chinese freshwater cultured pearls (11–14 mm) surrounded by a 17-inch necklace featuring variously colored round Edison pearls (10.5–13.5 mm). Photo by Robert Weldon/GIA, ...

In November 2022, a parcel of 24 approximately 0.5–1.2 ct spinel crystals, described as cobalt-diffused, were obtained directly from a treater by the research team at GIA in Bangkok. Of these, seven ...

GIA has been performing color stability testing on some sapphires for decades (Crowningshield, 1969). More recently, the stability test has been implemented to identify pink sapphires that can be ...

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 ...