![]() ![]() ![]() The intricate design and varying colour patterns of shells is mainly dependent on the diet of the animal the shell covers. They are often used whole and drilled so that they can be threaded. Throughout the history shells of many types and from many different kinds of animals have been popular as human adornments. ![]() Shells are organic minerals composed of calcium carbonate. While the colour of Sapphires can be changed by intense heat and radiation, it is stable for daily wear jewellery. They are heated or irradiated to produce colours such as greens, yellows or even blues. It should be noted that many Sapphires can be treated to enhance or change their colour. They can be found in Brazil, Tanzania, Sri Lanka, Kashmir, Thailand, Madagascar and Australia. These sapphires are cut into cabochons to display this effect. Some sapphires show a 3-point or 6-point star or asterism. Various shades of blue result from titanium and iron substitutions in the aluminium oxide crystal lattice. The most desirable sapphires are generally those with an intense blue colour with plenty of sparkle and life. Sapphires tend to be translucent or transparent and have high amounts of refraction. Sapphire is any colour of the mineral corundum other than red, those are called ruby, (see above) corundum is composed of aluminium oxide. Improvements used include colour alteration, improving transparency by dissolving rutile inclusions, healing of fractures (cracks) or even completely filling them. Almost all rubies today are treated in some form (of which heat treatment is the most common practice) and rubies which are completely untreated and still of excellent quality command a large premium. Jade is mined in the regions of Canada, Australia, United States and Taiwan. Nephrite is usually only green and creamy white, while jadeite can have the full range of jades colours. Not until the 19th century that a French mineralogist determined that jade was in fact two different materials. Nephrite and jadeite are resistance to breakage and chipping and due to their toughness they made a superior weapons and tools for early man. The term "jade" refers to two different, yet similar semi-precious metamorphic mineral gemstones, Jadeite and Nephrite. A species of hard nut sometimes called vegetable ivory or "tagua"is gaining popularity as a replacement for ivory. The 1990 Convention on International Trade in Endangered Species (CITES) put a ban on international ivory sales to lessen the threat to endangered species by poaching. Ivory had been used for thousands of years for tools, implements and weapons and for carving and jewellery. Ivory is a hard, white, opaque substance that is the bulk of the teeth and tusks of animals such as the elephant, hippopotamus, walrus, mammoth and narwhal. It is found in Brazil, Pakistan, Russia, East Africa, India, Madagascar and Columbia, at this point in time the best emeralds come from Colombia. Clear stones with vibrant colour command the highest prices. The value of an emerald depends on cut, colour, clarity and carat. Emeralds can have many inclusions and flaws so can be brittle and liable to break. Origin of name emerald is said to be a Sanskrit word meaning green (Sanskrit is a classical language of India). The GIA fancy colour grading scale is: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Deep and Fancy Dark.Įmerald is a valuable Beryl that owes its colour to chromium or vanadium, which make it the bright green. The grading scale is based on the intensity of the colour. The colour of a fancy coloured diamond is measured differently to a normal diamonds. One out of 10,000 normal diamonds is a fancy colour diamond. Today, small quantities of Alexandrite are mined in Brazil, Sri Lanka, India, Myanmar, Tanzania and Zimbabwe.ĭiamonds come in all colours but these natural Fancy Colour Diamonds are rare and can be very expensive. That area was mined for over 60 years and still today Russian Alexandrite is considered the best quality. Alexandrite was discovered in the Ural Mountains of Russia in the 1830's, and named after tsaravitch Alexander, the future tsar. To make an enquiry about purchasing gemstones please contactĪlexandrite is a variety of chrysoberyl that displays a colour change depending on light conditions and the angle it is view from (pleochroism).The ideal colour change would be fine emerald green to fine purplish red, but this is rare and expensive. We can also supply and cut stones to fit settings if they are not stock sizes. If necessary we can supply stones on approbation (appro) for you to show your customer under no obligation to buy. We have suppliers who can provide the more unusual stones. Supply- we stock a large range of the most common gem stones including diamonds and can supply a variety of grades and sizes. ![]()
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