Alexandrite

Big Photo

India
2.00 carats
© Palagems

Alexandrite is a variety of Chrysoberyl the colour of which varies between dark grass-green and emerald-green. It was named after Czar Alexander II.

It displays a color change (alexandrite effect) dependent upon the nature of ambient lighting. It is green in daylight, and light red in artificial incandescent light. To accentuate this peculiar character the stone must be cut of a certain thickness, the difference in colour being much less marked in a stone cut with little depth.

Until comparatively recent times alexandrite was found only in Russia, in the emerald mines on the right bank of the Takovaya, a small stream east of Ekaterinburg in the Urals.

Alexandrite Gemstones by Colour

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

Alexandrite Gemstones by Size

This table shows distribution of Alexandrite 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:0.07 cts
Heaviest:3.55 cts
Average:0.45 cts
Total photos:28
Do you have a larger Alexandrite? Why not upload a photo?
0.07ct to 0.42ct0.42ct to 0.77ct0.77ct to 1.11ct1.11ct to 1.46ct1.46ct to 1.81ct1.81ct to 2.16ct2.16ct to 2.51ct2.51ct to 2.85ct2.85ct to 3.20ct3.20ct to 3.55ct
General Information
A variety or type of:Chrysoberyl
Photos of natural/un-cut material from mindat.org
Synthetic Alexandrite
Synthetic alexandrite: Colour change - daylight: green to blue-green; incandescent light: red to violet-red. Transparent; Hardness 8.5; RI 1.740 - 1.756; Birefringence 0.007 - 0.010; Biaxial/+; SG 3.70 - 3.72; Pleochroism: red/orange-yellow/green; Inclusions: Flux method: flux and crucible (platinum) residues; Pulling method: slightly curved growth lines, black bubble-like inclusions; Hydrothermal method: swirl-like growth inhomogeneties, dark bubble-like residues, flat liquid inclusions; Fluorescence: SW and LW red - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 25
Physical Properties of Alexandrite
Mohs Hardness8.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity3.69 to 3.81
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical Properties of Alexandrite
Refractive Index1.739 to 1.770+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterBiaxial/+,-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence0.007 to 0.013
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
PleochroismRed stones - strong trichroism: dark red - orange - dark green; Green stones - strong: dark green - orange - dark red
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Colour
Colour (Daylight)Green
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Colour (Incandescent Light)Red
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Colour (Chelsea Filter)Red
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Causes of ColourColor-change, Cr3+ in octahedral coordination
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent
Walter Schumann, Gemstones of the world (2001)
Fluorescence & other light emissions
Fluorescence (General)Weak red, synthetic: common stronger reactions
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Crystallography of Alexandrite
Crystal SystemOrthorhombic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Inclusions in Alexandrite
Mica platelets, apatite, rutile, healing cracks, multi-phase inclusions, hollow tubes - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 25
Further Information
Mineral information:Alexandrite information at mindat.org
Significant Gem Localities
Australia
 
  • Western Australia
    • Cue Shire
      • Poona
Groat, L.A., Giuliani, G., Marshall, D.D., and Turner, D. (2008): Ore Geology Reviews 34, 87-112.
    • Dowerin Shire
MinMag 66(6):985-1002
Brazil
 
  • Bahia
    • Campo Formoso ultramafic complex
      • Pindobaçu
Pinto and Pedrosa-Soares (2001)
    • Curaçá river valley
      • Jaguarari
  • Goiás
    • Minaçu
Petersen et al. (2002)
  • Minas Gerais
    • Antônio Dias
      • Hematita
; Emeralds of the World English extraLapis Vol. 2 2002 pp46-51
    • Ferros
Cassedanne and Roditi (1993)
Czech Republic
 
  • Bohemia (Böhmen; Boehmen)
    • Liberec Region
      • Jizerské Mtn (Iser Mtn)
geological prospecting, 2008 - 2009, Czech geological Organization
India
 
  • Chattisgarh (Chhattisgarh)
    • Raipur District
Michelou (2006)
Madagascar
 
  • Fianarantsoa Province
    • Horombe Region
      • Ihosy District
        • Ilakaka Commune
Giuliani, G., Fallick, A., Rakotondrazafy, M., Ohnenstetter, D., Andriamamonjy, A., Ralantoarison, T., Rakotosamizanany, S., Razanatseheno, M., Offant, Y., Garnier, V., Dunaigre, C., Schwarz, D., Mercier, A., Ratrimo, V., and Ralison, B. (2007): Mineralium Deposita 42, 251-270.
Myanmar
 
  • Mandalay Region (Mandalay Division)
    • Pyin-Oo-Lwin District
        • Kyatpyin Central
Themelis, Ted, 2008, Gems and Mines of Mogok.
        • Kyatpyin North
Themelis, Ted, 2008, Gems and Mines of Mogok.
        • Mogok Valley
Themelis, Ted, 2008, Gems and Mines of Mogok.
Russia
 
  • Urals Region
    • Middle Urals
      • Sverdlovskaya Oblast'
Hochleitner (2005)
          • Malyshevo
Hochleitner (2005)
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
Gemexplorer.org
Econ Geol (1981) 76:733-738
  • Western Province
    • Kalutara District
Tanzania
 
  • Arusha Region
    • Dumbawanga District
http://www.ganoksin.com/borisat/nenam/tanzania-mines.htm
Emeralds of the World English extraLapis Vol. 2 2002 pp24-35
  • Ruvuma Region
    • Tunduru District
Milisenda et al. (1997)
USA
 
  • New Mexico
    • Rio Arriba Co.
      • Petaca District
Northrop, Minerals of New Mexico, 3rd rev. Ed., 1996
Zimbabwe
 
  • Masvingo
    • Masvingo (Fort Victoria)
[www.johnbetts-fineminerals.com]
J. E. Shigley et al. (2010), Gem Localities of the 2000s, Gems and Gemology, Fall 2010, pp. 188–216
Copyright © Jolyon & Katya Ralph 1993-2017. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.