One can so easily be captivated by the beauty and enchantment of fine coloured gemstones. Coloured gemstones are usually little understood and very underrated; some brief information on this fascinating subject will give some understanding and appreciation.
There are over 3000 identified minerals: although over 100 of these are considered gemstones, only about 50 are commonly used in jewellery.
Gemstones are generally minerals or rocks, which, when cut, faceted and polished display ‘beauty’. Some gemstones, such as amber, jet and coral are organic in formation. . Coloured gemstones are beautiful, rare and durable, they are collectible and can be set in jewellery
Gemmologists use technical specifications to classify gemstones.
The same 4 C’s (carat, cut, clarity, and colour) used to determine Diamond quality and characteristics are utilised for colour gemstones.
Of all the 4 C’s, it is colour that is the most important. Colour choice is very personal, there is no right or wrong colour. It is a common perception that the darker the colour, the better the stone. If the colour is too dark, the stone can be dull and lifeless. The beauty of a coloured gemstone is largely judged on the strength and depth of colour saturation, tone, hue and brightness.
Overall, a fine coloured gemstone must be pleasing to the eye.
Not all gemstones are practical for everyday wear mostly due to the varying degrees of hardness. The ‘durability’ or hardness of a gemstone (how easily it may scratch or break) is measured using the ‘Mohs’ scale of hardness. The scale runs between the numbers one to ten, with diamond top at ‘10’ the hardest and talc numbering ‘1’ the softest.
It is an acceptable fact of the industry that a high percentage of gemstones produced today have received some form of ‘treatment’. The most common being ‘heat treatment’. The gemstone is heated to a high temperature which enhances the natural colour: generally this is permanent and irreversible. In many instances, heat treatment can be regarded as a continuation of the earth’s natural performance. Many emeralds are commonly and acceptably oiled to enhance colour and conceal inclusions.
Gemstones were traditionally categorised into ‘precious’ and ‘semi-precious’ stones, however this is quite misleading as some ‘semi-precious’ stones may have a value far higher than that of a ‘precious’ stone. Jewellery is produced using many different coloured gemstones, the most popular, well established being ruby, sapphire, and emerald. Beautiful coloured gemstones, much underestimated, such as amethyst, aquamarine, citrine, topaz, tourmaline, peridot, zsavorite and more, too numerous to list, are finally becoming better known and included within many jewellery ranges.
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Rubies and Sapphires are of the same scientific mineral species, ‘Corundum’. On the Mohs scale they score ‘9’ second only to the diamond in hardness. The colour of a Ruby is always a hue of red, however sapphires are found in a vast spectrum of colours. Fine rubies vary in colour hue according to source but should radiate warmth, depth and liveliness. Blue is the main and most popular colour of sapphire, and can be found in all tones from a ‘Ceylon’ light, bright blue to a deeper intense velvety blue. Other ‘Fancy’ sapphire colours are pink, yellow, mauve, green, orange and white; the more clear and vivid the colour, the more valuable the fancy sapphire. The most valuable fancy sapphire is the ‘padparadscha’, orange-pink or pinkish-orange in colour.
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Emeralds belong to the ‘Beryl’ family; aquamarine also belongs to this family.
An emerald is not as hard as a ruby or sapphire and rates 7½-8 on the Mohs Scale.
The finest emeralds are of a deep, lively transparent ‘emerald’ green, (colour varys according to source area) however most are clouded by inclusions referred to as ‘jardin’. Emeralds are brittle and because of this, can be vulnerable, most are ‘oiled’ to fill and disguise cracks and enhance colour. They need special care and handling and should not be immersed in water or chemicals.
An exciting new gemstone of very recent discovery (1967), Tanzanite, is relatively unknown. A beautiful stone with a magnificent deep rich violet/blue hue. Only located in one unique source in Tanzania makes it rare and desirable. It rates 6½-7 on the Mohs Scale and needs to be worn and treated with care.
If you are interested in coloured gemstones and would like more information, please come in and see our current range. For a Bespoke piece of jewellery, we would be delighted to share our passion and show you a selection of loose coloured gemstones,
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