Spinel

Big Photo

Myanmar
1.22 carats
© Palagems

Spinel classifies a whole group of related minerals; only a few are of gemstone quality. The species gemologists designate as spinel occurs in all colors, the favorite being a ruby-like red.

Large stones are rare.

Spinel Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 
 
 
 
 
 
 
 

Spinel Gemstones by Size

This table shows distribution of Spinel gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.17 cts
Heaviest:61.45 cts
Average:2.56 cts
Total photos:146
Do you have a larger Spinel? Why not upload a photo?
Significant stones
Catherine the Great's Ruby414 cts
Timur Ruby361 cts
Catherina Spinel146 cts
0.17ct to 6.30ct6.30ct to 12.43ct12.43ct to 18.55ct18.55ct to 24.68ct24.68ct to 30.81ct30.81ct to 36.94ct36.94ct to 43.07ct43.07ct to 49.19ct49.19ct to 55.32ct55.32ct to 61.45ct
General Information
Varieties/Types:
Ceylonite - A spinel containing Fe2+
Gahnospinel - A Spinel rich in zinc
Pleonaste - Iron rich Spinel.
Chemical Formula
MgAl
 
2
O
 
4
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Significant stones
ImageNameWeightCountry of OriginCurrent Owner
Catherine the Great's Ruby414.30 ctsAfghanistanRussian State
Timur Ruby361.00 ctsThe British Crown.
Catherina Spinel146.43 ctsTajikistanUnknown
Black Prince's RubyAfghanistanCrown Jewels of the United Kingdom
Photos of natural/un-cut material from mindat.org
Spinel Treatments
Weigel (1923) gives early references on the heat treatment of spinel and reports that purple and pink spinels change to yellow above 1000°C, but may revert on cooling; blue spinel changes to green at 900°C and to yellow above 1200°C and this color change does not revert. Red spinels were reported to have had their color improved by a heat treatment which removes a brownish components and leaves a pure red (R. Crowningshield, unpublished information).
Synthetic spinel (Nassau, 1980) is usually grown by the Verneuil technique with an excess of Al2O3 to make growth easier. At the large excess composition, MgO · 5Al2O3, the resulting clear product is unstable and fine crystallites of alumina precipitate on annealing. This forms a strong schiller, yielding a fine moonstone imitation (Nassau, 1980; Breebart, 1958). The refractive index of 1.73 is quite different from the 1.53 of moonstone, as is the specific gravity of 3.64 to 3.66 compared to 2.57.
Spinel triplets have been used to imitate emerald, ruby, and even tanzanite; fading can occur if the dyes used are not stable – Nassau (1984)
Synthetic Spinel
Synthetic spinel (flux grown): colour - red, blue; Transparent; Hardness 8; RI 1.716 -1.719; Isotropic; SG 3.58 - 3.62; Inclusions: flux residues; Fluorescence for red synthetic spinel: SW and LW - red.
Synthetic spinel (flame fusion grown): All colours; Transparent, (opaque: lapis lazuli-like); Hardness 8; RI 1.720 - 1.740; Isotropic; SG 3.58 - 3.80; Inclusions: gas bubbles, rarely curved growth lines, distinct anomalous birefringence (undulatory extinction); Fluorescence: Colourless: LW commonly green, SW commonly white to bluish; Blue: LW occasionally red, SW occasionally blue; Green: SW commonly green; Yellow: LW and SW commonly green; Yellow-green: LW commonly green; Red: LW and SW commonly red - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 22, 23
Physical Properties of Spinel
Mohs Hardness8
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity3.54 to 3.70
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Cleavage QualityIndistinct
Walter Schumann, Gemstones of the world (2001)
More from other references
FractureConchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Spinel
Refractive Index1.710 to 1.735+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterIsotropic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Anomalous double refractionMore from other references
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
Dispersion0.020
Arthur Thomas, Gemstones (2009)
ChatoyancyRare star 4/6
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Colour
Colour (General)Red, pink, orange, blue, violet, blue-green
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Colour (Chelsea Filter)Pink to red: inert to fluorescent red. Rare cobalt blue: reddish.
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Causes of ColourViolet to purple, Cr3+ in octahedral coordination and Fe2+ in tetrahedral coordination. Cobalt blue, Co2+ and Fe2+ in tetrahedral coordination. Bluish green Fe3+ and Fe2+ in tetrahedral coordination. Green (synthetic spinel), Cr3+ in octahedral coordination. Pink to red, Cr3+ in octahedral coordination
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Red spinel: strong - red; blue spinel: weak - reddish, green.
Walter Schumann, Gemstones of the world (2001)
Fluorescence (Short Wave UV)Pink to red: inert to reddish. Blue: inert. Rare cobalt blue: normally inert.
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Fluorescence (Long-Wave UV)Pink to red: inert to red-(orangy). Blue: greenish. Rare cobalt blue: weak to moderate red. Colorless and light green: inert to moderate orangy-red.
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Fluorescence (X-RAY)There is a moderate glow of crimson colour for red and pink spinels. Some purple to mauve specimens glow plum-colour to lilac. Other specimens respond green.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Spinel
Crystal SystemIsometric
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitOctahedra though some specimens may show dodecahedron or cube faces.
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Geological Environment
Where found:Spinel is formed at high temperatures as an accessory in igneous rocks, in regionally and contact metamorphosed limestones and in other contexts.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Spinel
(Parallel rows of) tiny octahedrons - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 3
Spinel octahedrons, boehmite tubes, apatite, octahedral negative crystals, healing cracks - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 21
Further Information
Mineral information:Spinel information at mindat.org
Significant Gem Localities
Afghanistan
 
  • Kabul
    • Surobi District (Sorobi District)
Hughes (1994)
Cambodia
 
  • Krong Pailin Municipality (Pailin Municipality)
Hughes (1994)
China
 
  • Fujian
    • Sanming
    • Ding'an Co.
      • Penglai
  • Jiangsu
    • Nanjing
Madagascar
 
  • Anosy
[var: Pleonaste] Pezzotta (1999)
  • Ihorombe
    • Ihosy District
      • Ilakaka Commune
Milisenda et al. (2001)
Myanmar
 
  • Kachin State
    • Mohnyin District (Moe Hnyin District)
      • Hpakant Township (Hpakan; Phakant; Phakan)
Smith and Bosshart (2001)
  • Mandalay Region
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Bernardmyo
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
          • Lay-tha Taung
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Chaung-gyi
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kathé (Kathe)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kin (Guard Post)
Ted Themelis (2008) Gems & mines of Mogok
        • Kyatpyin Central
          • Baw-lon-gyi (Big Ball)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kyatpyin North
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kyauk-Pyat-That
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
          • Yadanar-kaday-kadar
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Marble Ark
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
          • Pyaung-pyin
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
          • Dattaw-taung (Dattaw hill)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • On-dan
Ted Themelis (2008) Gems & mines of Mogok
Hughes (1997)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
    • Yamethin District
Ted Themelis (2008) Gems & mines of Mogok
  • Sagaing Region (Sagaing Division)
    • Katha District
      • Wuntho Township
Ted Themelis (2008) Gems & mines of Mogok
Pakistan
 
  • Gilgit-Baltistan (Northern Areas)
    • Gilgit District
Hammer (2004)
Russia
 
  • Primorsky Krai
    • Roshchino
      • Kedrovaya river
  • Sakha Republic (Yakutia)
    • Aldan Shield
      • Aldan
Evseev (1994)
Sri Lanka
 
  • Central Province
G. Zoysa (2009)
  • Sabaragamuwa Province
    • Ratnapura District
Dissanayake et al. (2000)
Dissanayake et al. (2000)
Dissanayake et al. (2000)
[var: Gahnospinel]
  • Uva Province
    • Badulla District
Milisenda and Henn (1999)
Tajikistan
 
  • Viloyati Mukhtori Gorno-Badakhshan (Viloyati Badakhshoni Kuni)
    • Pamir Mts
      • Khorog Region
        • Shakhdara Range
      • Pyandzh River Valley
Gemexplorer.org
Bowersox and Chamberlin (1995)
Tanzania
 
  • Morogoro Region
    • Mahenge
Hyrsl (2001)
Hyrsl (2001)
Hyrsl (2001)
Quinn and Laurs (2004)
  • Ruvuma Region
    • Tunduru District
Pardieu (2007)
Thailand
 
  • Kanchanaburi Province
    • Bo Phloi District
  • Trat Province
    • Bo Rai District
USA
 
  • California
    • San Luis Obispo Co.
      • San Luis Obispo
Kunz, George Frederick (1883), American gems and precious stones: Mineral Resources U.S., 1882: 486; Kunz, George Frederick (1905a), Gems, jewelers’ materials, and ornamental stones of California: California Division Mines Bulletin 37, 171 pp.: 47; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 346.
Vietnam
 
Pardieu and Senoble (2005)
Pardieu and Senoble (2005)
Gemexplorer.org
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