Ruby | Red Variety of Corundum

What is Ruby?

Ruby is one of the original four precious gemstones, although the term 'precious' is now rarely used.

A captivating gemstone known for its deep red colour, ruby is the red variety of the mineral corundum, the second hardest mineral after diamond.

Ruby is composed of aluminium oxide with trace amounts of chromium, which is the reason for its colour. Aluminium oxide is a chemical compound of aluminium and oxygen.

Ruby's chemical composition is almost identical to sapphire. Although red corundum is known as ruby, all other colours are sapphire.

The similarity between ruby and sapphire has only been fully understood since the beginning of the 19th century. Until then, red garnets and spinels were also believed to be rubies.
The Black Prince's Ruby and Timur Ruby were later found to be spinels.

The name 'ruby' comes from the Latin 'ruber', meaning 'red'.

Colour is the most important factor when determining the value of rubies. The finest-grade gemstones are highly sought after and command extraordinary prices.

Almost all rubies have minor imperfections or anomalies. Millions of years ago, while growing deep within Earth's core, the chromium responsible for the red colour also caused fissures and cracks within the crystal. Very few enjoyed the right conditions to grow undisturbed and crystallise to perfection.

An important mining area for rubies during the 1990s was a small town in northeastern Myanmar (formerly Burma). The first rubies discovered there were not classified as gem-grade stones. This was because they displayed two colours, a purple-to-black core and bright red periphery.

It was some time before it was discovered that the shade of red could be deepened by heating the stone, which increased its value dramatically.

Ruby can be found in several locations worldwide. About 90% are heat-treated to improve colour.

They're usually heated before being cut. An unheated ruby is considered to be extremely unusual.
Ruby is believed to have been the first stone in the first row of the high priest breastplate. This religious garment was worn during biblical times by the Jewish high priest.   

Ruby is the birthstone for July. On the Traditional Birthstone Chart, onyx is an alternative.

Rubies are associated with love, passion, vitality, and courage. They have been worn by royalty throughout history and have strong cultural significance.

Article Photos

The photo at the top of our article and the pop-up photo of the ruby are royalty-free images.

The second photo is courtesy of Stan Celestian. The third is courtesy of Géry Parent. Images are clickable and redirect to the original photo.