Rubies are actually red sapphires. Sapphires and rubies are made of Aluminium Oxide (Al2O3, otherwise known as corundum) with trace deposits of chromium (Cr) or other minerals which give them colour (as the name Chromium would indeed suggest). Sapphires can be any colour; but if red (i.e. from light pink through to purple), they are called rubies.
It is only since the mid 19th Century that this has been so. Before that time, all red gemstones - such as garnets and spinels - were thought to be rubies. (Two of the British Crown Jewels, though referred to as the Black Ruby and the Timur Ruby, are not actually rubies at all, but spinels.)
Red is the colour of love and rubies have long been associated with love and romance. Love songs in many languages refer to ladies' ruby lips. Ruby was the second most popular name given to baby girls in England in 2007. The boy's name Reuben is less common, but comes from the same root. The Thai word for ruby can be a girl's name, a pomegranate (which has ruby-like seeds) or a popular edible fish, the red hybrid form of Nile tilapia, which is hugely (and deservedly) popular in many delicious Thai dishes. The Sanskrit word for ruby is ratnaraj - or royal gem - and Indian royalty indeed used to claim ownership of any particularly fine rubies found in the dominions. These rubies would be treated with the reverence due to a king and brought to court on an elephant with great ceremony!
The precise gradations of red in rubies are what mainly decide their value. Some rubies - called star rubies - have crystal structures that refract light through the stone in a star effect. Jewellers call this 'asterism'. In the rarest and most sought after star rubies, a twelve pointed star 'appears' as the gem is held to light. Four or eight pointed stars are more common.
The colour term 'pigeon-blood red' is associated with Burma - specifically mines near the town of Mogok in North-Eastern Burma. Now controlled entirely by the Burmese Military Government, with access denied to most foreigners, these rubies are off-limits to buyers from many countries. The town of Mong Hsu in Shan State, Burma, is now also famous (or infamous) for rubies - with controversy in the trade over the flux healing of rubies that come from there. Mong Hsu rubies were discovered only in the 1990s - and they're unusually dark - sometimes almost purple. While heat-treating to clear minor occlusions is fairly standard for rubies produced worldwide, Mong Hsu rubies are usually flux healed - an irreversible process which both changes the colour and closes up faults. This is a process which many in the ruby business are coy about - and many gem buyers disapprove of the practice - particularly as some unscrupulous dealers omit to mention that the stones have been treated in this way.
Rubies are also produced in Thailand - and these tend to be small and of a dark red with a brownish tinge, though some remarkably high quality stones appear from time to time. Mined in the South East of Thailand, traditional methods are still used to extract them.
In Africa, rubies are mined in Tanzania, Kenya, and more recently, large deposits have been found in Mozambique.
Small rubies and sapphires are used by jewellers for decorating pieces of jewellery for example as the eyes on frog cufflinks. Larger rubies are made into rings and cufflinks.
Tim Gardener invites you to visit http://www.jewellerymen.com for more information about heraldic engraved jewelry, gemstone cufflinks and gifts or sign up for our monthly newsletter at http://eepurl.com/oIvP. Thank you.
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