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RECOGNIZING GEMSTONES
The colour, sparkle and rare beauty of gemstones have fascinated mankind for thousands of years and are an integral part of some of our most collectable creations.
Gemstones range from precious diamonds, rubies and emeralds to the corals, turquoises and opals which were popular with the Victorians.
Jewellers have used a tremendous range of materials over the centuries to create their wares, depending on what they could find and the whims of fashion, but the flash and fire of gemstones, and the richness and iridescent subtleties of their colour, have ensured their popularity down through the ages.
In modern times, they have often been imitated in coloured glass or plastics, or synthesized in chemistry labs. Learning to recognize the real thing can save you from making some very expensive mistakes; when you go out buying, always take a magnifying glass with you and examine any gemstones carefully. If you've any doubts at all, leave the piece alone.
AMETHYST A member of the quartz family, amethysts can vary from pale lavender to deep violet in colour. The deeper the shade, the more valuable the stone; the finest are a rich purple, flashing with hints of red.
Used from antiquity for bishops' rings and for crucifixes, amethysts were also popular with the Georgians and early Victorians. They fell out of favour until the early 20th century, when they were a favourite stone of art nouveau designers, who combined them with opals and moonstones
for a delicate, moonlit effect. Glass imitations lack warmth and are generally a vivid mauve in colour.
CORAL Coral is not strictly a stone at all, but the external skeleton of the coral polyp, collected in the Mediterranean and off the coast of Japan. The colour ranges from white through pale pink (known as Angel Skin) to dark red. Capable of being carved and polished, coral is ideal for brooches (especially cameos), beads, rings and charms. In its natural, 'twiggy' state, known as branch coral, it was also used to make necklaces.
Coral was thought to be protection against witches and enchantment; good luck charms were often attached in bunches to a carved coral hand. Necklaces and suites of jewellery were made in ropes'; minute beads of coral were strung together, then these strands were twisted together. This type of jewellery was very delicate and difficult to repair, making it rare and costly
today. Imitation coral is general made of plastic, and is often far too orange. The real thing has a harder, more glassy feel.
OPALS The opal is an unusual stone; it's semi-transparent, not particularly hard and not crystalline in structure. It may shrink in time with loss of water. It is valued for its flashes of iridescent colour. The most valuable form is the opaque black opal, which is actually dark blue or green. The fiery colors show up vividly against the dark background. White or milk opals ar cloudy white and filled with tiny bubbles of gas, and their iridescence is more muted. Mexican water opals are almost colourless, while fire opals are orange-red in hue.
The 'pattern' seen in the opal is important. Harlequin has the same colour i l small regular patches which flash impressively. Pin-point has small patches and is not as vivid. Flame opal has
bands and streaks.
Although fire opals are sometimes facet-cut, others are always cut in a flattish cabochon. If the piece is thin, it may be hacked with a thicker piece, making a kind of sandwich known as a doublet. A triplet has a protective covering of clear crystal.
Opals are very porous and should be washed only in clean fresh water to retain their sparkle. They will absorb soapy water, spoiling the look of the gem. Comparatively soft, opals should be stored away from other jewellery.
PERIDOTS Members of the olivine family, peridots are a bright, clear, almost lime green. They were most popular in the Victorian era when they were set in gold, mounted alone or with seed pearls, and used for delicate pendants or small brooches. They were usually cut in emerald style
for brooches and pendeloque (pearshaped) for pendants. A variety found in Arizona is golden brown.
RUBIES Perfect rubies are clear and transparent. They are second only to diamonds in hardness and value, and large ones are more valuable than diamonds of the same size, as very few sizeable rubies are found to be free of flaws. The finest stones come from Burma and are a rich, dark, red, known as 'pigeon's blood'. Another dark ruby came from Siam (Thailand) and has a brownish tinge like the garnet. Some types of garnet are known as 'Ceylon', 'Bohemian', 'Colorado' or 'Arizona' rubies, and it's important not to be misled by this.
A pale, rose-coloured ruby is found in Ceylon, but what it lacks in depth of colour it makes up for in sparkle.
TURQUOISE Turquoise has been used decoratively for at least 5,000 years. In Victorian times it was known as the Turkey stone, from the country where it was mined. It can vary from a rich blue-green (a deep blue variety is known as Persian turquoise) to a pale
green colour.
It's usually cut as a cabochon and set in gold, often combined with pearls. It was found in large quantities in Tibet, India and China, and was prized by the Aztecs. In Colorado and New Mexico it was set, uncut, in silver and worn by the native American peoples. Turquoise is porous and stones can easily be discoloured by grease or perfume.
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Gemstones
