With all the modern innovations in cutting, the exacting proportions of the Tolkowsky Brilliant cut seem to endure. Many of the “named” cuts are little more than a minor tweak of the Tolkowsky Diamond Cut.
Properties of Diamonds
- Diamond Crystal – Isometric (Cubic)
- Crystal Habit – octahedra, cubes, elongated or flattened crystals, or flat twinned crystals.
- Luster – Adamantine; uncut crystals look greasy
- Hardness – 10, about 4.5 times harder than corundum
- Toughness – good
- Cleavage – perfect, octahedral (4 directions)
- Specific Gravity – 3.514 to 3.518
- Refractive Index – 2.4175 in sodium light. Among the highest R.I.s of any gem material.
- Birefringence – none, isotropic
- Dispersion – very high, 0.044
- Ultra Violet Fluorescence – many but not all diamonds fluoresce blue, green, yellow or reddish in both long and short wavelength u.v. light.