Carat weight, or mass, is just one of many gemstone properties measured at GIA (box A). Measurements of physical dimensions and facet angles of polished gemstones, assessment of color and ...

ABSTRACT In southeast Vietnam, gem-quality anorthoclase is found as megacrysts in Cenozoic alkali basalt. The crystals are transparent to translucent with vitreous luster and can be near-colorless, ...

CARLSBAD, Calif. – June 2, 2025 – Beginning later this year, GIA (the Gemological Institute of America) will start using descriptive terms to characterize the quality of laboratory-grown diamonds and ...

A group of remarkable bright yellow inclusions in a partially polished 2.43 ct orangy pink morganite from Madagascar (figure 1) recently caught our attention. The beryl was identified by a combination ...

Figure 1. This cross section through ancient thickened continental lithosphere and underlying mantle shows the two major depth intervals of diamond formation. The majority of mined diamonds originate ...

Nacreous pearls are commonly constructed from layers of stacked aragonite platelets. In recent years, however, GIA laboratories in Bangkok, Hong Kong, Mumbai, and New York have reported unusual pearls ...

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, ...

On January 24th 2024, Wim Vertriest, GIA Manager of Field Gemology, gave GIA’s first student lecture of the year at the GIA World Headquarters in Carlsbad, California. In this lecture, Wim explored ...

A well-known collector mineral, wavellite (Al 3 (PO 4) 2 (OH) 3 •5H 2 O), is named after its discoverer, British surgeon Dr. William Wavell. Wavellite mineral specimens seen on the market often occur ...

The perceived color of light after passing through a polished wafer of any uniaxial material can be calculated using transmittance spectra (both polarized and unpolarized) and the incident light angle ...

THE LINK BETWEEN ECLOGITE AND DIAMONDS 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 ...

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 ...