Did you know that sapphires and rubies are actually the same mineral called corundum? And did you know that sapphires can be found in more colours than the rainbow?
Why is a ruby called a ruby and a sapphire a sapphire if they are made from the same mineral? Well, the short answer is that when rubies were originally found they did not know that the were the same mineral as the beautiful blue sapphire. The names for both the stones come from the Latin denoting their names – Rubeus meaning red for Ruby and Saphirus meaning blue for Sapphire. Little did they know that sapphires can come in a stunning array of colours when they named the stone.
Scientifically, both sapphires and rubies are a crystalline form of aluminium oxide Al203 with trace elements such as chromium, iron or titanium which determine the colour of the corundum. These trace elements create the wide range of colours found in corundum crystals – from colourless to black and then every colour of the rainbow.
When is a ruby a ruby and not a sapphire? This is a very good question and the line is not clearly defined.
Before the 20th Century pink sapphires were described as pink rubies, but sometime during the 20th century someone decided to call pink rubies pink sapphires. This may be due to the rarity of gem quality rubies which are much rarer than diamonds. So perhaps the desire to own these stunning rare gemstone has created a demand for a restrictive definition.
Judging colour is very subjective – what one person sees as red another person may see as pink. The pinky/red border is debatable, but when the chromium levels are high there is no doubt as to the sumptuous beauty of the pigeon blood ruby.
All the colours of the rainbow
When we traditionally think of sapphire – a rich, royal blue colour springs to mind. The Duchess of Cambridge’s engagement ring is a perfect example. Sapphires, however, come in a myriad of stunning colours. The reason for these colours is again down to the trace elements (my inner science geek is happy!).
The blue sapphires gain their colour from a mixture of iron and titanium and the shade of blue depends on the percentages of these elements.
But blue is only one of the beautiful colours found in sapphires. Greens, yellows, oranges, purples, pinks – all unique and all stunning.