A ruby is a pink tae bluid-reid coloured gemstane, a variety o the mineral corundum (aluminium oxide). The reid colour is caused mainly bi the presence o the element chromium. Its name comes frae ruber, Laitin for reid. Ither varieties o gem-quality corundum are cried sapphires. The ruby is considered ane o the fower precious stanes, thegither wi the sapphire, the emerald, an the diamond.[1]

Naitural ruby crystals frae Winza, Tanzanie
CategoryMineral variety
(repeatin unit)
aluminium oxide wi chromium, Al2O3:Cr
Creestal seestemTrigonal (Hexagonal Scalenohedral), symbol (−3 2/m), space group R3c
ColourReid, mey be brounish, purplish, or pinkish
Creestal habitVaries wi locality. Terminated tabular hexagonal prisms.
CleavageNa true cleavage
FracturUneven or conchoidal
Mohs scale haurdness9.0
Speceefic gravity4.0
Refractive indexnω=1.768–1.772
PleochroismOrangey reid, purplish reid
Ultraviolet fluorescencereid unner longwave
Meltin pynt2044 °C
Major varieties
SapphireOny color except shades o reid
Corundumvarious colors

Prices o rubies are primarily determined bi colour. The brichtest an maist valuable "reid" cried bluid-red, commands a lairge premium ower ither rubies o seemilar quality. Efter colour follaes clarity: seemilar tae diamonds, a clear stane will command a premium, but a ruby wioot ony needle-lik rutile inclusions mey indicate that the stane haes been treatit. Cut an carat (wicht) are an aa an important factor in determinin the price.

References eedit

  1. Precious Stones, Max Bauer, p. 2