Ruby is one of two varieties of gemstone minerals that make up the Corundum family of minerals, the other mineral being Sapphire. Ruby is rarer and more valuable than Sapphire, partially attributed to the need for chromium to produce the rich and vibrant red colour, which is a rare element in nature.
Rubies are named for their distinct red colour, the latin for red is ‘ruber.’ This highly lustrous gemstone reflects light off its facets nearly as well as diamond. Ruby is the birthstone for July, and is gifted for forty-year wedding anniversaries. Ruby is well placed within the ‘big three’ of coloured gemstones, as it can command the highest price per carat of all coloured gemstones.
Both rubies and sapphires are part of the corundum mineral species. This means that their crystal structures are identical, save for the colouring elements within them. The lustrous red colour of the ruby is caused by chromium within its crystal structure. The colour can vary from a reddish purple, to a pinkish red, to a pure red with a hint of blue, known as pigeons blood to the jewellery trade. Rubies can also fluoresce, and it is this fluorescence that can intensify their lustrous red colour in daylight.
One highly distinctive type of ruby is a ‘star ruby.’ This is caused when the light reflects from aligned needle like inclusions within the stone causing a ‘star’ effect that shimmers upon the surface of the stone when it is moved.
The most renowned rubies, like those from Myanmar, the Himalayas, and northern Vietnam, typically form in marble. They’re found in hexagonal shaped crystals that are distributed irregularly within the surrounding marble.