Some titanium alongside the iron will produce the beautiful shades of blue for which sapphire is so famous.Īn orange or pink sapphire is formed when some chromium (rather than titanium) is mixed in with the iron and, if there is sufficient chromium, the gemstone becomes a ruby (which is simply the name given to what is essentially a red sapphire). For example, if there is some iron present then the sapphire can take on a yellow or green colour. Most of these foreign elements are some type of metal.

However, it is when some other elements are added that we see the amazing range of colours that a sapphire can possess. A piece of corundum without any impurities present is colourless (i.e. So how is it that they are different colours?Ĭorundum is what is called an allochromatic gemstone, which means that its colour comes from small amounts of impurities within the crystal. That is to say, it is all made from the chemical compound, aluminium oxide. Scientifically speaking, all corundum (both sapphire and ruby) is created equally in terms of its chemical composition. However, there’s a lot more to the colour of these stones than one might think.īoth of these precious gemstones belong to the same family of stones, called corundum. There is a common misconception that all sapphires are blue and all rubies are red.

Blue sapphire and ruby together