Back to gem encyclopedia

Sapphire

The name “sapphire” can also apply to any corundum that’s not ruby red, another corundum variety.

Responsive image

Responsive image

See gem as
Polished
Rough

Tools

Research

A sugar plum–like frosted zircon cluster in blue sapphire. Photomicrograph by Taku Okada; field of view 1.05 mm.

“Sugar Plum” in Titanium-Diffused Blue Sapphire

Taku Okada, August 29, 2025

A sugar plum–like frosted zircon cluster is observed in a blue sapphire.

Read More

Figure 1. The 2.65 ct sample in immersion with brightfield illumination showing the typical spiderweb effect of diffused stones. Photo by Féodor Blumentritt.

Diffusion-Induced Blue Spinel-Like Layer on Natural Sapphire

Féodor Blumentritt, Guillaume Zuber, Candice Caplan, and Franck Notari, August 29, 2025

Three natural sapphires exhibiting a surface layer of gahnite are studied at the GGTL laboratory.

Read More

Gabriela Farfan (right), Coralyn W. Whitney curator of gems and minerals for the Smithsonian National Museum of Natural History, accepts the original Gems Keep Giving pin from Hayley Henning, chairperson of the organization. Photo by Jennifer Stone-Sundberg.

Gems Keep Giving

Jennifer Stone-Sundberg and Tao Hsu, June 5, 2025

The nonprofit organization Gems Keep Giving aims to improve global small-scale mining and gem-cutting communities.

Read More

Prismatic elongated zircon in Kashmir sapphire. Photomicrograph by Narint Jaisanit; field of view 2.88 mm.

Prismatic Zircon in Kashmir Sapphire

Narint Jaisanit, June 5, 2025

Elongated zircon inclusions display attractive birefringent interference colors in a blue sapphire from Kashmir.

Read More

Synthetic sapphire before exposure to short-wave ultraviolet radiation. Photo by Jian Xin (Jae) Liao

Irreversible Photochromism in Synthetic Sapphire

Axle Estrella and Tyler Smith, June 5, 2025

The first documented case of corundum with irreversible photochromism encountered at GIA.

Read More

Figure 2. An assortment of rough sapphires (5–10 mm in diameter) extracted from the new mining area displaying characteristics typical of stones from the Rock Creek deposit, including many with a yellow “yolk” at the center. Courtesy of Potentate Mining.

Update on Montana’s Rock Creek Sapphire

Tao Hsu, June 5, 2025

Potentate Mining expands its mining operation and hosts the first Montana sapphire tender in Bangkok.

Read More

Figure 1. This Mozambique ruby contains needles and bands of particles before heating (left). The inclusions did not show any signs of alteration after heating at 900°C for 5 hours in air (right). However, the development of the 3309 cm–1 series in the FTIR spectrum was detected in this stone after heating, providing evidence of low-temperature heat treatment. Photomicrographs by Suwasan Wongchacree; field of view 1.75 mm.

The 3309 cm^–1 Series in Sapphire and Ruby: A Focus on FTIR Peak Position Variation

Wasura Soonthorntantikul and Aaron C. Palke, June 5, 2025

Investigates the correlations between peak positions in the 3309 cm^–1 series with trace element concentrations for ruby, metamorphic and basalt-related blue sapphire, and laboratory-grown sapphire.

Read More

Green musgravite crystals observed in a faceted green sapphire. Darkfield and fiber-optic illumination. Photomicrograph by Titapa Tanawansombat; field of view 1.8 mm.

Rare Musgravite Crystal in Green Sapphire

Titapa Tanawansombat, November 1, 2024

A surface-reaching crystal in a green sapphire is identified as musgravite.

Read More

Iridescent partially healed fissure observed in a 4.13 ct blue sapphire. Photomicrograph by Kanako Otsuka; field of view 2.12 mm.

Rainbow-Colored Partially Healed Fissure in Blue Sapphire

Kanako Otsuka, November 1, 2024

An iridescent partially healed fissure is observed in a blue sapphire from Sri Lanka.

Read More

Figure 1. Blue sapphires from the Matepwende area in southern Tanzania. Most of the production consists of low-clarity material in matrix. Only a very small percentage (usually weighing less than 1 ct) is clean enough to be faceted. Photo by Vincent Pardieu.

New Production of Sapphire from Matepwende, Tanzania

Aaron Palke and Vincent Pardieu, November 1, 2024

Reports on the study of sapphire samples from a newly discovered source in southern Tanzania.

Read More

Load More

This Month's

Featured Gems

reading

Peridot

Found in lava, meteorites, and deep in the earth’s mantle, yellow-green peridot is the extreme gem.

reading

Fancy Color Diamond

Dazzling brilliance. Captivating color. These are the planet’s most valued gems.

reading

Diamond

Diamonds are among nature’s most precious and beautiful creations.

reading

Emerald

Emerald is the bluish green to green variety of beryl, a mineral species that includes aquamarine.

reading

Citrine

Citrine is the transparent, pale yellow to brownish orange variety of quartz.

View the Gem Encyclopedia