how hard is a diamond?
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Material Formula Refractive\nindex(es)\n589.3 nm Dispersion\n431 – 687 nm Hardness\n(Mohs'\nscale) Density\n(g/cm3) Thermal\nCond. State of\nthe art
Diamond C 2.417 0.044 10 3.52 Excellent (Natural)
Glasses Silica with Pb, Al, &/or Tl ~ 1.6 > 0.020 < 6 2.4 – 4.2 Poor 1700 –
White Sapphire Al2O3 1.762 – 1.770 0.018 9 3.97 Poor 1900–1947
Spinel MgO·Al2O3 1.727 0.020 8 ~ 3.6 Poor 1920–1947
Rutile TiO2 2.62 – 2.9 0.33 ~ 6 4.25 Poor 1947–1955
Strontium titanate SrTiO3 2.41 0.19 5.5 5.13 Poor 1955–1970
YAG Y3Al5O12 1.83 0.028 8.25 4.55 – 4.65 Poor 1970–1975
GGG Gd3Ga5O12 1.97 0.045 7 7.02 Poor 1973–1975
Cubic Zirconia ZrO2(+ rare earths) ~ 2.2 ~ 0.06 ~ 8.3 ~ 5.7 Poor 1976 –
Moissanite SiC 2.648 – 2.691 0.104 8.5–9.25 3.2 High 1998 –
Quartz Silica 1.543 – 1.554 7- 2.50 – 2.65 Ancient
csv/203-csv/385.tsv