Ruby is one of the two main gemstones in the corundum mineral group - a species of crystalline formed gemstones – along with sapphire.
Ruby gets its name from the Latin word ‘rubens’ meaning red. This is because rubies, like peridot, are amongst the only gemstones which occur in a single colour. This type of gemstone is described as idiochromatic.
The mineral group, corundum, naturally creates clear crystallines. It is only when certain chemical elements are present in a corundum crystal does it become a ruby or a sapphire. Rubies are available in a spectrum of rich reds due to the traces of chromium present. Chromium produces a pink tone in corundum, it is only when there is enough chromium in the gemstone to create the red hue that it can be considered a ruby. The traces of chromium in a ruby determine its variant of red, the possible colours of a ruby include deep red, pinkish red, purplish red, orangey red and brownish red. The most desirable colour range is a pure vibrant red, known classically as “ruby red” to a slightly purplish red.
Ruby is the birthstone for July and the gemstone for the 15th and 40th wedding anniversaries.
In addition to the ruby’s bright colour, its desirability derives from its hardness, durability, lustre, and rarity. Transparent rubies of large sizes are even rarer than diamonds. The corundum variety (rubies and sapphires) rate 9 on the Mohs scale of hardness – second only to diamonds. This hardness and durability make the ruby a superb gemstone for jewellery pieces worn daily and can make a colourful alternative to the traditional diamond engagement ring.