![]() The gems with a black colour base and a white upper layer are called “true” or “Arabic onyx.” ![]() The most common onyxes are those with white and black layers. The rarity and value of white diamonds are based partly on how closely they achieve ‘colourlessness’ - the more colourless the diamond, the rarer and more expensive it gets.įor centuries, artisans have carved intricate and attractive cameos using black and white onyx the most popular of which are cabbed or faceted solid black onyxes.Ī type of chalcedony, onyx is a form of microcrystalline quartz that is distinguished by its straight, nearly parallel layers or bands of colour, allowing highly-skilled gem carvers to work on layers to create intaglios and cameos with extraordinary depth and contrast. The hues range from colourless – similar to a drop of pure water - to clear stones with tints of light yellow, light brown or grey. On the other hand, the term ‘white’ usually attributed to colourless diamonds that fall within the D-to-Z colour GIA scale or chart, is surprisingly not purely white at all. The stones are subjected to high-temperature/lowpressure treatment, which graphitises the fractures to make them turn black.Īlternatively, artificial irradiation of off-colour diamonds produces a dark green hue to make them appear black. Many begin as grey, which is heavily included and fractured. Most black diamonds used for jewellery have been treated to induce their colour. However, a fine natural-colour black diamond is a beauty in itself and makes it distinct yet more affordable than other diamonds. Since these diamonds are heavily included, cutting and polishing them requires expertise and must be set with great care. Typical natural-colour black diamonds are completely opaque, with a high lustre and achieve an almost metallic appearance. These inclusion concentrations are responsible for the colouration, allowing natural black diamonds to achieve the colour ranging from near-colourless to brown or olive green. The distinctive optical and physical properties of the diamond enable it to possess the highest possible lustre among transparent gemstones, also known as ‘adamantine lustre’ after the Greek word ‘Adamas’, which means ‘invincible’ and which be taken to mean ‘diamondlike’, given diamond’s hardness.īlack diamonds are known to achieve their colour from large quantities of minute mineral inclusions such as pyrite, graphite, or hematite that are distributed throughout the stone. It is the only gem made from a single element, which is 99.95 per cent carbon and the other 0.05 per cent comprise one or more trace elements whose atoms are not part of the stone’s basic chemistry but influences its shape and colour. ![]() In ancient Chinese philosophy, black and white are often represented by “yin” and “yang” which best describes how opposites or contrary forces co-exist to establish balance and maintain the natural order of everything in the universe.īlack and white gemstones hold similar levels of attraction – and mystery – which makes them popular and sought-after jewellery pieces.Ĭonsidered one of the most precious and hardest materials on earth, diamonds are typically formed between 150 kilometres beneath the earth’s crust under intense pressure and temperature. Such is the case of black and white, the opposites of the colour and energy spectrum. Since the dawn of time, people have been fascinated with contrasts – the existence of opposites and where extremes become vital elements in the balance of nature. Jeweller explores the globe to find out which of the black and white gemstone varieties are out there. Despite their simplicity in colour, black and white gemstones continue to captivate people in many cultures around the world.
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