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Spinel

The Black Prince’s Ruby. The Timur Ruby. For centuries, spinel, the great imposter, masqueraded as ruby in Europe’s crown jewels.

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Stunning Color

The finest red spinel colors are pure red to slightly purplish red hues of medium to medium-dark tone.

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Cut for Brilliance

Spinel is most often cut in cushion and oval shapes; when properly proportioned it has excellent brilliance.

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Chromium

Like ruby, the color of red spinel is due to traces of chromium.

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Nature’s Perfection

Spinel belongs to the cubic crystal system and its characteristic crystal shape is an octahedron, which looks like two back-to-back pyramids.

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Perfect for Jewelry

Like ruby, spinel is found in alluvial deposits; it ranks 8 on the Mohs scale and has good toughness, making it a durable gem for jewelry.

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Collector’s Favorite

Well-formed spinel crystals are in high demand among mineral collectors.

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Research

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Peer Reviewed (14)

Topics

Color (13) Optical Properties (4) Cut (3) See All Topics

Topics

Gemology (85)
Inclusions (23)
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Identification (14)
Color (13)
History (11)
Chemical Composition (10)
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Enhancement (4)
Mineralogy (4)
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Physical properties (3)
Precious Metals (3)
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Gemstones

Diamond (61) Sapphire (54) Ruby (46) Emerald (40) Pearl (38) See All Gemstones

Gemstones

Spinel (138)
Diamond (61)
Sapphire (54)
Ruby (46)
Emerald (40)
Garnet (38)
Pearl (38)
Opal (29)
Tourmaline (27)
Diamond - Fancy Color (18)
Jade (16)
Amethyst (15)
Topaz (12)
Aquamarine (11)
Alexandrite (9)
Peridot (9)
Zircon (9)
Tanzanite (7)
Turquoise (6)
Moonstone (5)
Amber (3)
Iolite (1)
Kunzite (1)
Lapis Lazuli (1)
Morganite (1)
Sunstone (1)
XClear Selections
A strikingly textured crystal, likely a metal sulfide, is suspended within a pink spinel; viewed under darkfield and diffuse fiber-optic lighting. The step-cut facets on the stone’s pavilion provide a sense of depth to the image. Photomicrograph by E. Billie Hughes; field of view 3.4 mm.
Metal Sulfide in Spinel

E. Billie Hughes, February 2, 2026

A pink spinel hosts a richly textured, opaque metallic inclusion.

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A prismatic pargasite crystal against the pink faceted background of its spinel host. Photomicrograph by Tyler Smith; field of view 1.76 mm.
Suspended Pargasite Crystal in Pink Spinel

Hannah Wiggins, November 17, 2025

A euhedral prismatic pargasite crystal is identified in pink spinel.

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Parcels of rough pink spinel from Malawi, ranging from approximately 4 to 7 ct. Courtesy of Phoenix Gems.
Gem-Quality Spinel from Southern Malawi

Cristiano Brigida, June 5, 2025

Parcels of rough spinel recently mined in Malawi were offered at the AGTA show.

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A crystal inclusion in red spinel shown in darkfield illumination (left) and fiber-optic lighting (right). Photomicrographs by Isabelle Corvin; field of view 1.78 mm.
Suspended Crystal in Red Spinel

Isabelle Corvin, January 26, 2024

A crystal inclusion in red spinel displays rainbow colors under fiber-optic lighting.

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Stellate dislocations decorate the interior of a greenish blue spinel believed to be from Vietnam. Photomicrograph by Ezgi Kiyak; field of view 4.79 mm.
Large Stellate Dislocation in Spinel

Ezgi Kiyak, November 3, 2023

A greenish blue spinel displays a large network of needle-like dislocations clustered in a six-rayed star pattern.

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A precipitation of an unidentified mineral in a fissure of a purple spinel creates this highly intricate moiré pattern. A combination of oblique fiber-optic and darkfield illumination was used. Photomicrograph by Tyler Smith; field of view 2.90 mm.
Fissure with Moiré Pattern in Spinel

Tyler Smith, November 3, 2023

A precipitation of an unidentified mineral creates a complex moiré pattern in a fissure of a purple spinel.

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Morphological features of the tourmaline crystal included in the heliodor are visible; striations and triangular growth marks are present. A band of fluid inclusions is visible near the tip of the schorl tourmaline. Photomicrograph by Rhiana Elizabeth Henry; field of view 2.90 mm. Gift of Mark Mauthner, GIA Museum no. 37772.
Heliodor with a Large Schorl Inclusion

Rhiana Elizabeth Henry, November 3, 2023

An 8.33 ct rectangular heliodor displays two tourmaline inclusions and a thin band of fluids.

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Figure 1. Suite of faceted nickel-diffused spinel (0.67–1.01 ct) showing a range of color from blue to bluish green. Photo by Aaron Palke and Diego Sanchez.
Color Modification of Spinel by Nickel Diffusion: A New Treatment

Michael Jollands, Abadie Ludlam, Aaron C. Palke, Wim Vertriest, Shiyun Jin, Pamela Cevallos, Sarah Arden, Elina Myagkaya, Ulrika D’Haenens-Johannson, Vararut Weeramongkhonlert, and Ziyin Sun, August 4, 2023

Reports on a newly discovered treatment process for producing a deep blue color in natural spinel and proposes identification criteria.

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Figure 1. This faceted purple spinel, weighing 0.51 ct and measuring 5.20 × 4.17 × 3.10 mm, was reportedly from Tanzania. Photo by Jinlin Wu.
Forsterite in a Purple Tanzanian Spinel

Jinlin Wu, Hong Ma, and Huihuang Li, May 23, 2023

Examination of a purple spinel from Tanzania reveals a rare forsterite inclusion.

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Figure 1. Suite of faceted nickel-diffused spinel (0.674–1.009 ct) showing the range of color from blue to bluish green. Photo by Aaron Palke and Diego Sanchez.
Article
Color Modification of Spinel by Nickel (Ni) Diffusion: A New Treatment in the Gem Market

Michael Jollands, Abadie Ludlam, Aaron Palke, Wim Vertriest, Shiyun Jin, Pamela Cevallos, Sarah Arden, Elina Myagkaya, Ulrika D’Haenens-Johannson, Vararut Weeramongkhonlert, and Ziyin Sun, February 10, 2023

GIA researchers report on a new nickel-diffusion treatment used to modify color in spinel and present criteria for identification.

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