Ruby is one of the four original precious gemstones with the other three being Sapphire, Emerald and Diamond. Having said that, the term 'semi precious' is no longer favoured by gemmologists who now consider that all gemstones should be referred to as 'precious'.
Ruby is a variety of 'Corundum' (Aluminium oxide) which is the second hardest natural mineral on Earth behind the Diamond. Sapphire is also a variety of corundum so Ruby and Sapphire are scientifically the same gemstone with the colour being the only differentiating factor. The red colouration is caused mainly by Chromium and only red Corundum is entitled to be called Ruby, all other colours are classified as Sapphire. The similarity between Rubies and Sapphires has only been known since the beginning of the 19th century, up until then, red Garnet and Spinels were also thought to be Rubies. The 'Black Ruby' and 'Timur Ruby', both of which are in the British crown jewels, were incorrectly named and both are in fact Spinels. The name 'Spinel' comes from the Greek word for 'spark' and refers to its fiery red colour. The word 'Ruby' comes from the Latin 'ruber' meaning 'red'.
Colour is the most important factor in determining the value of fine Rubies. A good coloured Ruby, one that is pure and brilliant and more than three carats, will command an extraordinary price and is said to be the most valuable of all gemstones and has even been known to over take the Diamond.
It is extremely rare to find a perfect Ruby and the vast majority of Rubies have imperfections of some kind. This is because millions of years ago when Rubies were being created deep inside the core of the Earth, Chrome was the element which gave them their rich colour, but at the same time it was also responsible for causing a multitude of fissures and cracks inside the crystals. Therefore only a few Rubies were given the right conditions in which to grow undisturbed and to crystallize to form perfect gemstones.
A significant area for mining Rubies during the nineties was a small town called Mong Hsu in the North East of Myanmar (formerly Burma). When first mined, Rubies were not expected to be suitable for use in jewellery since they displayed two colours, a purple to black core and a bright red periphery. Only after it was discovered that the core could be turned to deep red by means of heat treatment did Rubies begin to gain great value.
About 90% of all Rubies are heated to enhance their colour. It is usually the rough material that is heated before cutting. A Ruby which is not heated is considered to be very unusual.
Ruby is thought to have been one of the gemstones in the high priest's breastplate or breastplate of Aaron. Rubies can be found in a number of locations worldwide.
Being graded 9 on Mohs scale of mineral hardness makes Ruby absolutely perfect for use in jewellery.
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