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Diamond: real vs fake

Every Diamond checkpoint on this site states a measurement, an accept range and how we arrived at it. No comparison photos we didn't shoot, no certificates.

Real vs fake guides
Fake Diamond Names: Moissanite, CZ and Rhinestones 15 measured checks How To Tell If a Diamond Is Real: 10 Measured Checks 14 measured checks
Checkpoints covered
  • Cubic zirconia 5.80 g/cm3 for cubic zirconia; diamond reads 3.52
  • Moissanite 0.043 birefringence, the gap between moissanite's two refractive indices of 2.648 and 2.691; diamond reads 0.000
  • Strontium titanate 0.190 dispersion, 4.3 times diamond's 0.044; Mohs 5.5 against diamond's 10
  • YAG 1.833 refractive index for yttrium aluminium garnet; diamond refracts at 2.417
  • GGG 7.08 g/cm3 for gadolinium gallium garnet; twice diamond's 3.52
  • Synthetic rutile 0.296 birefringence at 589 nm; diamond reads 0.000
  • White sapphire 4.01 g/cm3 for corundum; the measured band runs 4.00 to 4.10
  • White zircon 0.059 birefringence in high zircon; specific gravity 4.60 to 4.80
  • Colourless spinel 1.727 refractive index for colourless spinel; the full range runs 1.712 to 1.780
  • White topaz 1.63 refractive index for topaz, range 1.607 to 1.649; colourless material reads 3.56 to 3.57 g/cm3
  • Leaded glass 1.75 refractive index for lead glass, which runs 1.7 to 1.8; soda glass reads 1.5
  • Specific gravity 3.52 g/cm3 for diamond; 5.60 to 6.00 for cubic zirconia; 3.22 for moissanite
  • Diameter at one carat 6.45 mm across the girdle of a 1.00 ct round brilliant; a 6.5 mm cubic zirconia weighs about 1.65 ct
  • Dispersion 0.044 dispersion figure for diamond; 0.104 for moissanite; 0.058 to 0.066 for cubic zirconia
  • Facet edge doubling 0.043 birefringence in moissanite; 0.000 in diamond, which is singly refractive
  • Facet count 57 facets on a standard round brilliant; 58 when the culet is cut as a facet
  • Mohs hardness 10 on the Mohs scale for diamond; 9.25 for moissanite; 8.0 to 8.5 for cubic zirconia; 5 to 6 for glass
  • Thermal conductivity 2200 W per metre kelvin for diamond; about 400 for moissanite; under 3 for cubic zirconia
  • Table and depth percent 57 percent table width in a well cut round brilliant; 59 to 62.5 percent total depth
  • Girdle inscription 20 power of loupe that makes a laser inscription comfortably legible; 10 finds it
  • Setting metal mark 585 one of 375, 585, 750, 950 or PT950 stamped inside the shank
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