Ruby
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]
| Ruby | |
|---|---|
 Naitural ruby crystals frae Winza, Tanzanie | |
| General | |
| Category | Mineral variety |
| Formula (repeatin unit) | aluminium oxide wi chromium, Al2O3:Cr |
| Creestal seestem | Trigonal (Hexagonal Scalenohedral), symbol (−3 2/m), space group R3c |
| Identification | |
| Colour | Reid, mey be brounish, purplish, or pinkish |
| Creestal habit | Varies wi locality. Terminated tabular hexagonal prisms. |
| Cleavage | Na true cleavage |
| Fractur | Uneven or conchoidal |
| Mohs scale haurdness | 9.0 |
| Skinkle | Vitreous |
| Streak | white |
| Diaphaneity | transparent |
| Speceefic gravity | 4.0 |
| Refractive index | nω=1.768–1.772 nε=1.760–1.763 |
| Birefringence | 0.008 |
| Pleochroism | Orangey reid, purplish reid |
| Ultraviolet fluorescence | reid unner longwave |
| Meltin pynt | 2044 °C |
| Solubility | none |
| Major varieties | |
| Sapphire | Ony color except shades o reid |
| Corundum | various colors |
| Emery | Granular |
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- ↑ Precious Stones, Max Bauer, p. 2