AUCTION HOUSE HIGHLIGHTS

OPALS

Melanie Saleem of Elstob & Elstob charts the history of a fascinating gemstone

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pals are unique amongst precious and semiprecious stones, renowned for their mesmerising iridescence and ability to reflect back a huge variety of different colours. But their popularity has waxed and waned over the centuries, explains Melanie Saleem, jewellery expert at Ripon auction house Elstob & Elstob.

Thanks to their ethereal, otherworldly quality some ancient cultures associated opals with lightning. Others, including the ancient Greeks, treasured them because they believed these mysterious stones gave their owners the power of prophecy, says Melanie. In the UK opals took a sharp dip in popularity in the 1830s, gaining the reputation of being an unlucky stone – a change in attitudes often attributed to Sir Walter Scott. In 1829 the immensely popular novelist published Anne of Geierstein, in which a character who wears an opal amulet comes to a nasty end. Many superstitious readers decided to steer clear of the stone.

Queen Victoria, however, did her bit to turn the tide, not only enthusiastically wearing opals herself but giving them as gifts – excellent news for the nascent Australian opal mining industry.

Australian opals first came to the attention of mineralogists in the 1840s, and by the closing years of the 19th century Australian opal mining was booming. Today Australia supplies over 95% of the world’s opals.

COOL JEWEL

So what exactly is an opal? “Opals are largely composed of silica,” says Melanie, “and they form in cracks in host rocks. They have a fairly high water content, so it’s a good idea to store them well away from radiators and other strong heat sources otherwise they might expand and crack. Opals also get scratched fairly easily, so don’t let opal items rattle around in a jewellery box with harder stones.

“The structure of opal wasn’t fully understood until the 1960s – a discovery which made possible the creation of the synthetic opals that started appearing on the market in the 1970s. If you look closely you can usually tell the difference between a natural opal and a lab-created one fairly easily. A synthetic opal is composed of regular columns, and has a ‘lizard skin’ look to it.

“Genuine opals come in several different categories, with ‘white’ and ‘black’ being the two most well known. ‘White’ opals are the commonest kind, and have a milky overall colour. ‘Black’ opals, as the name suggests, have a darker body colour. They are more valuable than white opals, and the darker their background the higher the price they fetch.

“As a rule, the more different colours an opal contains, the more valuable it will be. Blues and greens are common in opals, reds less so. Black opals that show red are incredibly rare, and consequently very expensive. Rarer still are Mexican ‘fire’ opals, whose body colour is red rather than white or black.”

ROCK STEADY

“When an opal is described as a ‘boulder’ opal it means the opal is still attached to part of its host rock or matrix. What I particularly like about the late Victorian ring-mounted boulder opal shown here is that the stone is round, which is quite unusual; most opals in rings are oval or pearshaped. It also displays plenty of red tones.”

Opals and diamonds make an attractive combination and are often used together, as in both the black opal and diamond ring and the elegant festoon necklace shown here. Also illustrated is an attractive Arts and Crafts ring featuring a pear-shaped black opal set amongst twining silver vine leaves. “Opals were very popular with the Arts and Crafts movement, which celebrated stones for their beauty rather than their intrinsic value,” says Melanie. “The colours in this opal are especially intense, hence the high price.”

Like all minerals, opals are a finite resource, and jewellers have found clever ways of using pieces of opal that would otherwise go unsold. Opal ‘doublets’ and ‘triplets’, for example, contain only a thin slice of opal. Doublets have a layer of dark material laminated to the back of the translucent opal slice to give it the appearance of being a black opal. Triplets have both a backing layer and, on top, a clear layer, often made of rock crystal.

Doublets and triplets are usually mounted using a bezel setting to hide the sides of the opal ‘sandwich’, as is the case with the opal doublet ring shown here. “This ring probably dates from the second half of the 20th century,” says Melanie. “It’s a big statement piece with a lovely display of colour. Had this been an actual opal rather than a doublet it would undoubtedly have cost thousands of pounds rather than hundreds.” For more information about auctions at Elstob & Elstob visit elstobandelstob.co.uk or call 01765 699200.

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1. Victorian 18 carat ring featuring two black opals and four old-cut diamonds, hallmarked Birmingham 1892. Sold for £800.

2. 18 carat gold ring with a round boulder opal in a bezel setting, hallmarked Birmingham 1899. Sold for £950.

3. Arts and Crafts ring with a pear-cut black opal in a double claw setting representing fruiting vines. Sold for £2,000. 4. Late 19th or early 20th century black opal and diamond festoon necklace. Elstob & Elstob auction estimate £400 to £600.

5. Necklace of graduated black opal beads spaced by faceted rock crystal beads and an opal-set box clasp. Elstob & Elstob auction estimate £800 to £1,200. 6. Opal doublet ring featuring an irregularly shaped opal doublet in a bezel setting. Sold for £700.