These defects can sometimes devalue gemstones, although they can also increase the value of sapphires that exhibit asterism.Ĭarat – Sapphires range in size and can have a varying degree of carats.

It occurs when the sapphire is examined in direct sunlight or with intense light and results from needle-like inclusions of rutile or hematite.Ĭlarity – Blue sapphires tend to have better clarity than rubies, but they also often possess long, thin inclusions called ‘silk’. There is also a rare variety of sapphire that exhibits different colours in different lights this colour-changing gemstone can show hues of blue in daylight and hues of red under incandescent light.Īsterism – This is a star-like pattern on a cabochon-cut stone.

Secondary hues of green or grey can diminish the value of a sapphire. Different colours are caused by impurities in the gem yellow sapphires contain ferric iron, blue sapphires iron and titanium, and colourless sapphires have no contaminants, for example. The beautiful September birthstone is desired by many due to its superb properties that make any piece of jewellery high value:Ĭolour – The most valued hue is the rich cornflower blue that is most commonly associated with this gem.

Sapphire month