DigMyGem Gem encyclopedia

Spinel

Natural Faceted Gems

Spinel is a magnesium aluminium oxide mineral that crystallizes in the cubic system, often as sharp octahedra. It occurs in red, pink, orange, purple, blue, and other colors; chromium commonly produces red, while iron and other trace elements produce darker hues.

Identity

Material or variety
Spinel
Scientific or material identity
Spinel
Classification
Natural mineral or mineral variety
Composition or formula
MgAl₂O₄
Crystal system or structure
Cubic
Geological or manufacturing origin
Can form in more than one geological environment, or combines several materials.
Mohs hardness
8
Specific gravity
3.58 to 3.61

Origins

Myanmar · Sri Lanka · Tanzania · Vietnam

Appearance & optical properties

rich raspberry-red spinel.

History & discovery

For centuries red spinel was grouped with ruby under names such as balas ruby. The Black Prince’s Ruby entered English royal history in 1367 but is actually spinel; in 1783, mineralogist Jean-Baptiste Romé de l’Isle distinguished spinel as a separate mineral.

Uses & care

Common uses
Transparent spinel is faceted for rings, earrings, pendants, and other jewelry. Opaque or included material may be cut as cabochons, while well-formed octahedral crystals are collected.
Handling and cleaning
Warm soapy water is always safe. Spinel is hard and tough, but high heat may fade some colors; avoid ultrasonic or steam cleaning when fractures are present and protect facet edges from sharp blows.

Jewellery

5 pieces of Spinel jewellery. Learners earn each one in DigMyGem by learning words; until then it shows as a silhouette.

  • Silhouette of Black Prince's Ruby

    Black Prince's Ruby

    Crown

    A 170-carat cabochon red spinel, long mistaken for a ruby, set in the cross above the Cullinan II diamond on Britain's Imperial State Crown. It has belonged to English rulers since the fourteenth century.

  • Silhouette of Timur Ruby

    Timur Ruby

    Necklace

    A 352.54-carat polished red spinel bearing the engraved names of Mughal emperors and Persian shahs, set in a necklace for Queen Victoria in 1853. It is still part of the British Royal Collection.

  • Silhouette of Samarian spinel

    Samarian spinel

    Jewel

    At 500 carats the largest spinel known, taken to Iran by Nader Shah and now part of the Iranian Crown Jewels. A small diamond covers a hole once drilled through it.

    Photograph of Samarian spinel
    Photo: Robert M. Lavinsky, CC BY-SA 3.0, via Wikimedia Commons
  • Silhouette of Spinel of the Great Imperial Crown

    Spinel of the Great Imperial Crown

    Crown

    A 398.72-carat red spinel, once called the Menshikov Ruby, that tops the Great Imperial Crown of Russia above a diamond cross. It is held in the Kremlin Diamond Fund.

    Photograph of Spinel of the Great Imperial Crown
    Photo: Алмазный фонд СССР / Под ред. акад. А. Ферсмана. - Москва : Издание народного комиссариата финансов СССР, 1924-1925. Вып. 3. - 1925. - 45, [3] с., LI-LXXV л. табл.; тираж 300 экз., Public domain, via Wikimedia Commons
  • Silhouette of Three Brothers (jewel)

    Three Brothers (jewel)

    Pendant

    A lost 14th-century Burgundian jewel of three large rectangular red spinels arranged around a central diamond, later part of the English Crown Jewels and worn by Elizabeth I before it vanished after 1645.

    Photograph of Three Brothers (jewel)
    Photo: Original painter unknown. Photograph by Peter Portner, Historisches Museum Basel., CC BY-SA 4.0, via Wikimedia Commons

Sources