![]() ![]() So, whilst opaque star sapphires may have bright, well-defined stars, their colour can be dull and unattractive. Star sapphire colourationĬolour saturation in star sapphires decreases as opacity increases. For this reason, star sapphires are becoming increasingly more difficult to find. Unfortunately, as the price of transparent rough sapphires has escalated in recent years, many star sapphires are subjected to extreme heat and sold instead as transparent stones. The best stones are translucent to semi-transparent. ![]() They can be heated to intensify their colour, but this must be done at modest temperatures and with extreme care to avoid ruining the rutile silk. Most star sapphires remain untreated, but they can be subjected to treatments to improve their colour or artificially induce asterism. However, you should be wary of stars that are too perfect – many man-made star sapphires exist on the market, and this is a tell-tale sign that the star is painted on. They generally have uneven tops or bottoms, which is often necessary to allow the star to be properly orientated and to display the best asterism. This Art Deco star sapphire ring has a clear star in the bottom centre of the grey-blue stone.Ī star sapphire needs to have the right amount of rutile to allow it to be cut and polished, and they are often cut into cabochons with high domes to maximise the star effect. This causes the light to reflect in a rather unique way, causing a star to form on the stone. However, in black star sapphires, both their colour and stars are caused by the shiny mineral hematite. The optical phenomenon within a star sapphire is known as asterism.Īsterism – from the Latin ‘astrum’, meaning star – is caused by small needle-like inclusions of the mineral rutile. They have long been a highly coveted and prizes stone, used both for aesthetic purposes and as a talisman across centuries. A star sapphire is a variety of sapphire which exhibits a unique reflection, giving the impression of a star trapped within the stone. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |