A ruby is a pink to blood-red gemstone, a variety of the mineral corundum (aluminium oxide). The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. The ruby is considered one of the four precious stones, together with the sapphire, the emerald, and the diamond.
Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions will indicate that the stone has been treated. Cut and carat (size) also determine the price.
Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions will indicate that the stone has been treated. Cut and carat (size) also determine the price.
Color:
Red, may be brownish, purplish or pinkish
Red, may be brownish, purplish or pinkish
Crystal habit:
Varies with locality. Terminated tabular hexagonal prisms.
Varies with locality. Terminated tabular hexagonal prisms.
hardness
9.0
Luster:
Vitreous
Refractive index:
~1.762-1.770
Pleochroism:
Orangey red, purplish red
Ultraviolet fluorescence:
red under longwave
Streak:
white
Specific gravity:
4.0
Melting point:
2050 °C
Solubility:
none
Diaphaneity
transparent
9.0
Luster:
Vitreous
Refractive index:
~1.762-1.770
Pleochroism:
Orangey red, purplish red
Ultraviolet fluorescence:
red under longwave
Streak:
white
Specific gravity:
4.0
Melting point:
2050 °C
Solubility:
none
Diaphaneity
transparent
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