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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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Tools

Overview

About Spinel

Until recently, spinel was an underappreciated gem with little consumer recognition. Increasing demand for ruby alternatives rekindled appreciation for spinel’s rich red color and history. In ancient times, southeast Asia’s mines yielded exceptional large spinel crystals, which became the treasured property of kings and emperors, often passing through many hands as spoils of war.

Spinel Description Spinel History and Lore Spinel Journey

Birthstones & Anniversaries

Spinel was recently added as an August birthstone, sharing this month with peridot and sardonyx. It has long been mistaken for ruby by emperors and monarchs. Many of the famous “rubies” of history were actually spinels.

Nat Thwe

Spinel crystals are so perfect, in Burma they are said to be nat thwe or “polished by the spirits.”


Black Prince

The famous 14th century Black Prince’s Ruby in the British Imperial Crown is actually a red spinel.


1783

Mineralogist Jean Baptiste Louis Rome de Lisle identifies spinel as a different mineral than ruby.


Facts

  • Mineral:   spinel
  • Chemistry: MgAl2O4
  • Color: red, orange, pink, purple, blue, black
  • Refractive index: 1.718
  • Birefringence: none
  • Specific gravity: 3.60
  • Mohs Hardness: 8

Where It's Found

map

Treatments

There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

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Synthetics

Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

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Imitations

Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

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gem love

Why We Love This Gemstone

1
Stunning Color

Singly refractive and often very transparent, red spinel rivals ruby’s color but it costs much less.

2
Amazing Chromium

Red spinel is colored by chromium, the same trace element that colors ruby and emerald.

3
Birth of Gemology

Distinguishing spinel from ruby gave birth to the science of gemology.

Quality Factors

An assessment of the following characteristics determines spinel’s value..

Color

quality factors

The most valued spinel colors are bright red, cobalt blue, and vivid pink and orange. Pale lavender is more affordable

Clarity

quality factors

Spinel with no visible inclusions is preferred. The more prominent the inclusions, the less valuable the gem.

Cut

quality factors

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

Carat Weight

quality factors

Fine-color spinel is rare above five carats. Most fine-quality rough is cut to non-standard sizes to save weight.

Spinel Quality Factors: The Comprehensive Guide

Research

Explore sources, gemological research, and the role of gems in history.

Some Gemological Challenges in Identifying Black Opaque Gem Materials

Mary L. Johnson, Shane F, McClure and Dino G. DeGhionno , Dec 1, 1996 Read Article

Flux-Grown Synthetic Red and Blue Spinels from Russia

Sam Muhlmeister, John I. Koivula, Robert C. Kammerling, Christopher P. Smith and Emmanuel Fritsch and James E. Shigley , Jun 1, 1993 Read Article

Gemstones of Pakistan: Emerald, Ruby, and Spinel

E. J. Gübelin , Sep 1, 1982 Read Article

'Cobalt-Blue' Gem Spinels

James E. Shigley and Carol M. Stockton , Mar 1, 1984 Read Article