Corundum

Corundum specimens for sale

87 for sale · $1–$500,000 USD

555 in the gallery

Corundum is a hard mineral with a trigonal crystal system and a relatively colorless to deep colored appearance when trace elements are present. Pure corundum is colorless, but chromium yields red corundum (ruby) and iron/tiberium-related elements produce blue (sapphire); other impurities can create yellow, green, or orange varieties. Faceted crystals are common in fashioning gem-quality specimens, and lustre ranges from vitreous to adamantine in well-formed crystals.

Formula
Al2O3
Rarity
Common
Stability
Stable
Collector interest
Very High Interest
Classification notes
Oxide; corundum-hematite group (Strunz 4.CB.05)

Key characteristics

Crystal system
trigonal
Mohs hardness
9
Specific gravity
3.95–4.1
Luster
adamantine, vitreous, pearly
Transparency
transparent, translucent, opaque
Color
colorless, white, gray, black, brown, red, orange, yellow, green, blue, violet, pink
Streak
white
Cleavage
none
Fracture
conchoidal, uneven
Crystal habit
prismatic, pyramidal, tabular, granular, massive
  • Gem mineral
  • Fluorescent: red, orange
  • Classic / historic

Buy Corundum specimens

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Where Corundum is found

Top localities

  1. Ratnapura54 specimens
  2. Mogok31 specimens
  3. Mysore17 specimens
  4. Mogok Valley7 specimens
  5. Kyauk-Pyat-That5 specimens
  6. Winza4 specimens
  7. Sri Lanka3 specimens
  8. Jegdalek ruby deposit3 specimens
  9. Mundarara Mine3 specimens
  10. Mysore District3 specimens

About Corundum

Notable sources include Myanmar and Sri Lanka, which have produced some of the most iconic ruby and sapphire crystals, alongside Madagascar, India, and Afghanistan for a broad range of corundum colors and crystal habits. Field collectors value well-formed crystals with clean faces, deep color, and minimal inclusions, while cabinet specimens showcase the mineral’s sometimes slender tabular or blocky forms. Corundum occurs in metamorphic and igneous settings, often forming in alumina-rich pegmatites, xenoliths, or crustal zones where high temperature and pressure drive crystallization.

For collectors, corundum offers both gem-quality material and striking crystal thumbnails. The diversity of color and the potential for large, sharp crystals make it a versatile target for museums and private displays alike, while the long history of gem cutting adds cultural resonance to well-documented localities.