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Diamond

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

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A new edition of Herbert Tillander’s book, updated by his daughter, Ulla Tillander-Godenhielm.

New Edition of Tillander’s Diamond Cuts in Historic Jewellery 1381–1910

GIA Staff, February 2, 2026

An updated edition of Herbert Tillander’s book is now available.

$Figure 1. A round brilliant-cut diamond set in the necklace exhibits the flash effect when tilted, a characteristic of fracture filling caused by the presence of a filler within a surface-reaching fracture. Photo by Gaurav Bera.$

Fracture-Filled Diamonds Detected in Mounted Jewelry

Sumit Vardawat, Ashok Prajapati, and Roxane Bhot Jain, February 2, 2026

The Mumbai laboratory reports on a jewelry submission containing fracture-filled diamonds.

Figure 2. This yellow-orange transparent crystal of almandine-pyrope garnet is a very rare inclusion in diamond. The example shown here has a typical somewhat rounded habit. Photomicrograph by Nathan Renfro; field of view 3.84 mm.

Quarterly Crystal: Almandine-Pyrope Garnet in Diamond

John I. Koivula and Nathan Renfro, November 17, 2025

A diamond octahedron from South Africa hosts a rare yellow-orange almandine-pyrope garnet crystal.

Figure 1. The diamond ring front view. Photo by Shunsuke Nagai

Diamond Ring Prize from an Arcade-Style Claw Game

Mari Sasaki, November 17, 2025

A diamond ring from a claw game in Japan is analyzed.

Figure 1. The 2.50 ct diamond in a dark environment around 10 s after deep-UV excitation to showcase its phosphorescence. Photo by Nick “Ka Chun” Chan.

Type IIa/IaB Diamond Showing Transient Type IIb Responses

Nick “Ka Chun” Chan and Satyaprasad Pradhan, November 17, 2025

A 2.50 ct natural type IIa/IaB diamond submitted to the Dubai laboratory shifts to type IIb after deep-UV excitation.

Figure 1. This 37.41 ct rough diamond has distinct pink and colorless zones. Photo by Tebogo Hambira.

Extraordinary Large Bicolor Natural Rough Diamond

Sally Eaton-Magaña, Kgotlaetsho Baatshwana, and Norma-Jean Osi, November 17, 2025

A 37.41 ct natural rough diamond with distinct pink and colorless zones is examined at GIA’s Botswana laboratory.

Figure 1. Examples of rough diamonds with shapes governed by various combinations of growth, breakage, and resorption. Specimens range from 1.08 to 28.08 ct, with the largest specimen measuring 27 mm in length. Photo by Evan M. Smith

Raw Brilliance: Nature’s Diamond Sculptures

Evan M. Smith, November 17, 2025

Showcases the diverse natural shapes of rough diamonds and explores how geological processes create their unique forms.

Figure 1. Examples of contact-twinned macle diamond crystals from South Africa. Left to right: a flat triangular macle with limited resorption (sample 11; 0.357 ct); an extensively resorbed variant of a flat triangular macle (sample 12; 0.411 ct); a very elongated flat macle with stacking growth layers on the octahedral faces, showcasing sharp edges and pointed apex corners (sample 13; 0.553 ct); a six-pointed star-shaped, poorly resorbed flat macle (sample 14; 0.747 ct). Photo by Tetsuya Chikayama; courtesy of Suwa & Son, Inc.

External Morphology and Internal Zonal Structure of Macle Diamond

Ahmadjan Abduriyim and Masao Kitamura, November 17, 2025

Investigates the morphological changes of macle diamonds during the growth process by exploring their three-dimensional internal zonal structure.

Article

Extraordinary Large Bicolor Natural Rough Diamond

Sally Eaton-Magaña, Kgotlaetsho Baatshwana, and Norma-Jean Osi, October 15, 2025

A 37.41 ct natural rough diamond with distinct pink and colorless zones is examined at GIA’s Botswana laboratory.

Figure 2. One of eight triangular limonitic faces in the 2.22 ct diamond crystal containing a phantom. Photomicrograph by Nathan Renfro; field of view 4.78 mm.

Quarterly Crystal: Unique Phantom in Diamond

John I. Koivula and Nathan Renfro, August 29, 2025

A diamond octahedron contains a three-dimensional phantom visible through all eight octahedral faces.

This Month's

Featured Gems

Peridot

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

Fancy Color Diamond

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

Diamond

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

Emerald

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

Citrine

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

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Diamond

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Peridot

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Diamond

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Peridot

Fancy Color Diamond

Diamond

Emerald

Citrine

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