Corundum vs Diamond

Property Corundum Diamond
Formül Al2O3 C
Kristal Sistemi Trigonal Cubic (Isometric)
Mineral Sınıfı 04 Oxides and Hydroxides 01 Native Elements
Mohs Sertliği 9.0 10.0
Renk Red (ruby), blue (sapphire), various colors Colorless, yellow, brown, blue, green, pink
Parlaklık Adamantine Adamantine
Çizgi Rengi Colorless None
Şeffaflık Transparent Transparent
Dilimlenme None Perfect octahedral {111}
Kırılma Conchoidal to uneven Conchoidal

Key Differences

  • Diamond (hardness 10) is harder than corundum (hardness 9) — the hardest natural mineral vs. the second hardest.
  • Diamond is pure carbon; corundum is aluminum oxide (Al2O3).
  • Diamond crystallises in the cubic system; corundum is trigonal.
  • Both are used as abrasives, but diamond abrades corundum, not vice versa.
  • Corundum gem varieties are ruby and sapphire; diamond gems are simply called diamonds.

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