When yellow to reddish-brown topaz is heated at a relatively low temperature, if chromium is present it turns a rich shade of pink or purplish-red. At just 500 degrees celsius (932☏) the colour of blue topaz begins to fade. This method of heating is used to add warmth to blue topaz after it's been irradiated. London and Swiss blue are left for considerably longer which is why these stones are more expensive.īy using conventional heat any colour of topaz can be enhanced.
Sky blue topaz is usually left untouched for a couple of months. That's because they must be securely stored away to allow any measurable levels of radiation to decay before they can be handled. Scientists believe gemstones that have been exposed to radiation pose no risk to human health. Swiss blue has an almost electric blue colour.Ĭolourless topaz was first irradiated to produce a blue stone in 1947. Exposure to heat changes a mineral's chemical composition which causes it to change colour. London blue has a more intense colour with a darker tone and deep saturation. The light blue coloured stone known as sky blue topaz is the most popular. Although many gemstones are irradiated, the practice is mostly associated with topaz. Stones can be heated through conventional methods in an industrial oven or through exposure to different types of radiation. Blue topaz is an incredibly popular gemstone that's widely used around the world.ĭepending on how colourless topaz is heated three different shades of blue can be produced. The vast majority is produced by heating the colourless stone. Crystals form within igneous rocks.īlue topaz does occur naturally but it's extremely rare. Topaz is a silicate mineral made up of aluminium and fluorine. It can also be found in white, yellow, grey, blue, orange, brown and green. Red, pink, violet and purple come from impurities of chromium. What Colour is Topaz?Īlthough topaz can be found in a wide range of colours the vast majority is colourless. Blue topaz is the birthstone for December on the modern chart with the mineral turquoise being an alternative. Pearl is the birthstone for November on the mystical birthstone chart. On the modern and traditional chart citrine may be used as an alternative. The state of Minas Gerais (which means general mines) in Brazil has long been the world's largest supplier.Īccording to the modern, traditional and ayurvedic birthstone charts topaz is the birthstone for November. Topaz can be found in several countries around the world. Pressure or a sudden change in temperature can lead to the stone becoming damaged. Carrying out a repair to a piece of jewellery featuring a topaz gemstone is difficult and risky. It's sensitive to heat and can break or shatter even when being heated gently at relatively low temperatures. It also chips very easily so it's a difficult stone to work with.įlaws or inclusions can increase the chances of topaz cleaving. This characteristic makes cutting and polishing topaz more difficult. Topaz breaks easily along specific planes of weakness in its crystal structure. Hardness and toughness in relation to rocks and minerals is not the same. Although topaz is one of the hardest minerals it's also very fragile. Mohs scale is a tool which grades the resistance of one mineral when being scratched by another. Topaz grades 8 on Mohs scale of mineral hardness. In both references the stone referred to as topaz is believed to have been peridot. A topaz is said to have been one of the twelve gemstones in the high priest breastplate. Topaz can be traced back even further and is mentioned in the Old Testament in the Book of Exodus. The ancient Roman author, naturalist and philosopher Pliny the Elder wrote about finding "topazos" on St John's Island in his encyclopaedia Naturalis Historia. The gemstone peridot which comes from olivine is known to have been available in abundance on the island of Topazios. Historians believe the name topazos was actually a reference to the mineral olivine although it's not possible to know for certain.
It's not known whether topaz was even known to ancient civilizations. It lies off the coast of Egypt and is known today as St.John's Island or Zabargad in Arabic.Īnother theory for the meaning of topaz is that it comes from the Sanskrit word "topas" meaning "heat" or "fire". The meaning of topaz is believed to come from a small island in the Red Sea once known as Topazios. Topaz Meaning Properties Facts and Photos Contents
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