Collecting guide: 5 things to consider when buying jewellery

David Warren, Senior International Jewellery Director, talks to Lavender Au about what withstands the whims of fashion

1. Art Deco-period Cartier

‘From the turn of the 20th century until the 1920s, Cartier held the wrists, necks and hearts of royalty and the international aristocracy in its beautifully bejewelled grip,’ says David Warren, Senior International Jewellery Director at Christie’s. Restlessly inventive, brothers Pierre, Louis and Jacques had, Warren explains, ‘an ethic that no one else shared. It was: never copy, always create.’

By 1909, Cartier shop fronts on Fifth Avenue, rue de la Paix and New Bond Street glittered with stones from far beyond New York, Paris and London. ‘They might bring back a 19th-century carved jade lion-and-cub figurine from China, put the lion on an onyx-and-coral stand with cabochon sapphire details, drill a hole through the top and fit a mystery clock made from a large faceted citrine,’ says Warren.


An Art Deco diamond bracelet, by Cartier. Designed as a wide old European and single-cut diamond pierced band of “fleurette” design, mounted in platinum and 18k gold, 1923. 7¼ in, with French assay mark and maker’s mark, in a Cartier red leather case. This piece and those below were offered in the Important Jewels sale on 16 June 2015 in New York. Sold for $461,000

Elsewhere, the intricate latticework of Islamic architecture might influence the shape or decoration of a vanity case or jewel, while the fall of tassels on an Indian turban might dictate the dangle of coral beads or a string of pearls.

Closer to home, Louis Cartier would send draughtsmen to make sketches of wrought-iron Parisian balconies that might become the filigree of a tiara. Because of its clean, linear style, Art Deco-period Cartier has proved particularly robust against the whims of fashion. ‘Jewels are worn with fashionable dresses,’ says Warren, however, ‘so fashion is crucial.’


2. Colours that make your spine tingle

Aside from its shape, cut and size, the most important quality in a gemstone is its colour: it should make your spine tingle. ‘Coloured diamonds are remarkably beautiful freaks of nature,’ says Warren. ‘And they are much rarer than white diamonds.’ An accidental inclusion of boron will turn a diamond blue, slippage of the lattice structure will make it pink, and radiation in the ground will turn it green.


A Coloured Diamond and Diamond Pendant Necklace. Suspending a pear-shaped diamond, weighing approximately 5.06 carats, trimmed with circular-cut diamonds, and a modified pear-shaped fancy purplish pink diamond, weighing approximately 1.68 carats, to the fine link neckchain, mounted in platinum, 16 in. Sold for $317,000

All must be tested to make sure the colours were created by nature, not man. Warren recommends the Gemological Institute of America (GIA) for diamonds and the Swiss laboratories for coloured gemstones. ‘Those laboratories have the best reputation,’ he says.

‘If you hold a wine bottle up to strong sunlight, you get close to the ideal dark-green colour of a Muzo-mine emerald,’ he continues. ‘For rubies, the perfect colour is a darkish pigeon-blood red. Too dark and it can look rather gloomy.’

One thing Warren likes to do is to to take the best stones from Christie’s jewellery auctions in Hong Kong, London and New York, and line them up. Differences difficult to explain then become apparent. ‘Kashmir sapphires are sometimes described as hazy or sleepy,’ he says. ‘They may contain masses of microscopic inclusions, even if they’re not visible to the naked eye, that create the hazy blue colour. By contrast, Ceylon stones tend to be quite transparent and glass-like.’


Left: A Sapphire and Diamond Ring. Set with a rectangular-cut Ceylon sapphire, weighing approximately 27.83 carats, flanked on either side by a triangular-cut diamond, mounted in 18k gold, with French assay mark and maker's mark. Sold for $845,000. Right: A Fine Sapphire and Diamond Ring. Set with a cushion-cut Kashmir sapphire, weighing approximately 9.97 carats, to the circular-cut diamond shoulders, mounted in platinum. Sold for $1,145,000

Small and fine is always preferable to large and opaque. ‘You might have a 50-carat emerald, but if it’s full of inclusions, who cares?’ Warren explains. ‘What you want is an 8-to-10-carat gem — worth $40,000 to $60,000 a carat — rather than a 50-carat stone that’s worth $2,000 to $3,000 a carat.’


3. Portability, price increases and the prestige attached to previous owners

According to Warren, jewellery rides out recession well. ‘After the 2008 collapse, people had less confidence in the financial markets or property, so they put their money into jewels,’ he says. ‘We have had our best-ever year every year since that date.’

The portability of jewels accounts for some of the demand. ‘You can’t buy a house in the middle of Paris, and when the market drops move it to London’ he eplains. ‘But you can fit diamonds into your top pocket.’

Warren has witnessed some incredible price increases. ‘If you had bought coloured diamonds in the 1970s and sold them in the 1990s, you would have made a big profit,’ he says. ‘And if you had bought them in the 1990s and were selling them now, your profit would be vast.’

The mystique of past owners can also add value. After a ferocious table-tennis match between Elizabeth Taylor and Richard Burton — two famous aficionados of the game — Taylor emerged the winner. Her prize was a diamond ring. She was rubbing her hands as the pair went shopping. What would she get — a 20-carat? A 50-carat? Burton more than fulfilled his promise, buying her three rings. But he chose the tiniest diamonds he could find in all the shops in Gstaad. Just over 40 years later, her Ping Pong rings, as they are known — set with diamonds of just half a carat each — sold at Christie’s New York for $134,500.

But not everyone is impressed by famous past owners. ‘I was on the telephone with a client in America who wanted to buy a beautiful pair of pearl earrings that were once owned by Queen Victoria,’ he recalls. ‘He won the lot at auction and said to me afterwards: “So who was this Victoria lady anyway?” Although the piece had a distinguished history, this individual wanted them solely for their quality.’

Geoff Young on brilliant diamonds, coloured sapphires, and how to find the perfect engagement ring

4. It’s not all about vintage

In recent years, contemporary jewellers have provoked fierce bidding wars. In the November sale last year, a parrot tulip bangle highlighted with a sprinkling of diamonds by the Paris-based jeweller JAR (Joel Arthur Rosenthal, see below) sold for $3,649,493, well above its estimate of $200,000–300,000.


A Gold, Diamond and Green Garnet 'Parrot Tulip' Bangle, by JAR. Designed as a sculpted gold flower, the two petals at the base forming the hinged cuff, enhanced by single-cut diamonds and circular-cut green garnets, 1994, flower size 9.5 cm, in pink leather fitted JAR case. Sold for $3,649,493 in our Geneva Magnificent Jewels sale in November 2014

There are brilliant contemporary designers working worldwide: Lorenz Bäumer in Paris, Vicente Gracia in Valencia, and Michelle Ong, Wallace Chan and Edmond Chin in Hong Kong. A client of Warren’s who owned some 1980s sapphire and diamond jewellery by Gérard sent it off to be redesigned by JAR. He returned a cross of five sapphires with a pavé diamond border.

‘I’m sorry for Gérard that his legacy didn’t live on in that piece,’ says Warren. ‘But it has become one of the top creations by a true genius, the contemporary equivalent of Fabergé. It’s a fat and chunky cross that makes you smile to look at. And the sapphires are so beautiful they make you cry.’


5. And one final piece of all-important advice

For aspiring collectors, Warren has one key piece of advice. ‘A silly advertisement I saw when I was young has stuck in my head: “It’s the fish John West reject that makes John West the best.” Collecting jewellery is like big-game hunting. You have to be patient and go for the right pieces.’

Main image at top: An Art Deco diamond pendant necklace. Suspending a detachable pear-shaped diamond, weighing approximately 16.24 carats, from a single-cut diamond line, to the old-mine cut diamond neckchain, mounted in platinum, circa 1920. Sold for $2,225,000

Follow David Warren on Instagram to see more stunning jewels — @davidwarrenchristies


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