Grossular crystals cut along specific orientations reveal a distinct trapiche structure.

Profiles the extraordinary life and work of Ben Kho, from a young entrepreneur in Cambodia to an award-winning gem cutter.

Describes the geology, mineralogy, and formation of granitic-composition pegmatites and provides a summary of their worldwide occurrences.

An overview of the Summer 2025 Gems & Gemology content.

Provides a comprehensive summary of the special optical effects in gemstones, including opalescence, chatoyancy, asterism, schiller, and iridescence, and investigates the submicron inclusions and nanotextures in each type of phenomenal stone.

GIA developed this guide so retailers can use fluorescence tests to help identify gems right in their own stores.

360-degree video of the Motswedi diamond.

A black opal cabochon set in a ring displays vivid orange play-of-color.

Presents the first scientific and historical study conducted on the 2.33 ct Winston Red, the fifth-largest known Fancy red diamond in existence.

Investigation in the Carlsbad laboratory reveals a pearl submission is not mabe as initially believed.

The Bangkok laboratory studies 35 loose non-nacreous pearls from a wide range of marine mollusk species.

Examination of a gigantic South Sea bead cultured pearl reveals an intriguing internal structure.

Archival research and gemological characterization reveal the geographic origin of two emeralds set in a pendant linked to Catherine de’ Medici, Queen of France from 1547 to 1559.

Learn about the principles, mechanisms, and characteristics of luminescence that create the impressive and memorable glow of gemstones.

Gemology has become a highly technical field employing analytical instruments for gem testing, driven by the need to address increasingly complex identification challenges in the marketplace.

Photoluminescence spectroscopy examines how gemstones absorb and emit light, uncovering crucial details about their identity and color origin through the detection of microscopic defects and impurities.

Infrared spectroscopy, specifically FTIR analysis, measures atomic vibrations to determine identity, cause of color, and potential treatments by analyzing how a gemstone absorbs infrared light.

GIA ensures accurate gemological measurements across its global laboratories through rigorous metrology practices, including systematic instrument calibration, validation from traceable standards, and continuous monitoring by trained staff to maintain precision and consistency.

UV-Vis-NIR spectroscopy measures how gemstones absorb and interact with light across the ultraviolet, visible, and near-infrared ranges, revealing crucial information about their composition, origin, and potential treatments.

GIA’s laboratories use advanced instrumentation and research to deliver accurate grading, identification, and origin determination for natural and laboratory-grown diamonds, colored stones, and pearls.