Golden Prism Jewellery

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Rubies

Colour: Varying red
Colour of streak: White
Mohs’ hardness: 9
Specific gravity: 3.97-4.05
Cleavage: None
Fracture: Small conchoidal, uneven, splintery, brittle
Crystal system: Hexagonal (trigonal), hexagonal prisms or tablets rhombohedrons
Transparency: Opaque, translucent, transparent
Fluorescence: Strong; ruby-red

 

 



Ruby is thus named because of its red colour.  The red colour varies with the individual deposits.   The most desirable colour is ‘pigeon’s blood’ pure red with a hint of blue.  The distribution of colour is often uneven, in stripes or spots.  As a ‘rough’ stone, ruby appears dull and  greasy but, when cut, the lustre can approach that of a diamond.  The hardest mineral after diamond,  although only 1/140th as hard, the next on Mohs’ scale of Hardness - 9.
Ruby has no cleavage, but has certain preferred directions of parting.   Because of its brittleness, care must be taken when cutting and setting.  Inclusions are common, they are not indicative of lower quality, particularly in average quality stones, but shows the difference between a natural and a synthetic stone.  The types of inclusion (mineral, canals or other cavities) often indicates the source area.  Included rutile needles produce a soft sheen (called silk). Ruby is one of the most expensive gems, large rubies being rare.