You’re buying jewellery wrong

Ah, the holidays.

It’s the perfect time to buy something significant for a special person. And it’s the perfect time to freak out about how, exactly, to do it.

Jewellery is an intensely personal way to express style. If you’ve got someone in your life with even the barest shred of personal style, approach the endeavour with eyes wide open and ears curled towards every hint of preferences that float your way.

It is possible to win this challenge. It just takes some effort.

The main thing is to know what you don’t know. So I met Fiona Druckenmiller at her Upper East Side shop in New York to seek her advice for buying gemstones. She’s got credibility: As one-half of the multibillion-dollar Druckenmiller fortune, she presides over FD Gallery, a six-storey townhouse full of treasures from the likes of Société Cartier, Van Cleef & Arpels, JAR, Verdura, Hemmerle, and Viren Bhagat. Walk through the heavy, double-door portal and you’ll find yourself amid glittering items worth hundreds of thousands of dollars apiece. Her clients range from Upper East Side doyennes and French financiers to young Asian entrepreneurs and Italian barons.

Druckenmiller wants to make it clear: “Just because you’ve bought an engagement ring doesn’t mean you know how to buy gemstones." It’s solid advice, and a great place to start. Here’s what else you need to know if you are in the market for some seriously fancy jewellery.

You can’t eyeball quality

Do you know the difference between heated and unheated rubies? Can you spot an emerald that has been oiled, versus one that contains no oil? Probably not. But those enhancements greatly affect the value of stones.

“People have been heating stones for hundreds of years to enhance the colour," Druckenmiller says. “But a Burma ruby that is unheated is going to be worth 10 or 20 times as much as a heated ruby from Africa."

As for emeralds, many have little fissures in them, because emerald can be brittle. Jewellers often use oil to make the cracks less visible. So an emerald with no oil will naturally be more valuable than one that has been altered.

The best way to find out what kind of quality you’re dealing with is to inquire, simply and directly. Question the seller as to where the jewel originated and how it has been treated. Ask to see the certification papers. And bring along an expert, or a well-trained friend, to act as backup and offer a second opinion.

At auctions, be persistent

If you do take your chances at public auctions and sales, be prepared to go up against dealers, retailers and brand-name houses such as Cartier and Van Cleef, which often buy back important estate- and museum-quality jewellery to keep in their archives and exhibit worldwide.

The major gem auctions—think Sotheby’s, Phillips, Bonhams, Christie’s—typically start in November in Geneva and run through December. Industry insiders who attend them “will be very involved" in the first group of auctions, Druckenmiller says. Then they retreat.

“When it gets to be a week before Christmas, they have likely already spent their money or they have gone on to other things—so you can find bargains," she says. “This will even happen just at the later end of night sales, when they are dropping out, or their attention wanders. But you have to be lucky. It’s a matter of being really vigilant."

Refuse to accept old certificates of authenticity

When you talk to a dealer or retailer, always request certificates of authenticity for any gem.

Look to ensure that the lab certification is from a trusted source, one that confirms the geographic origin, grade and quality of stones after the institute has determined an item’s gemological identity, alterations, and origin. The place where a gem originated is important because certain countries, regions and mines are renowned for the quality of their stones.

It’s also vital that certification papers are current. Two years old? Fine. Ten years old? Not acceptable. Lab technology has improved exponentially in recent years.

Don’t underestimate the law of supply and demand

The supply of top-notch vintage Cartier and Van Cleef jewellery and valuables declines yearly. But buyers in Asia continue to feed the region’s voracious demand for known and historic brands, including Tiffany, Hermès International SA and Chanel SA.

The imbalance elevates prices.

“It’s the historic names they know, so every year in those niche markets, the demand goes up and the supply goes down," Druckenmiller says. This is markedly different from buying something in a modern retail store, where lab-grown gems and cultivated pearls, plus costume-style jewellery and altered stones, can be supplied indefinitely.

Combat this by focusing your eagle eye on auction results. Those can give a good indication of current market rates.

“One thing you could do is ask whichever jeweller you’re working with, ‘Can you show me auction comps for similar items?’" Druckenmiller says. “That’s a really good way to get a yardstick on valuations. So if you’re looking at a Cartier art deco diamond bracelet, and you see a similar auction result, it might not be exactly the same piece, but if the width is the same, it can give you a good idea for what something similar might be worth."

If the dealer won’t share auction comps with you, walk away.

Know your audience

The biggest stumbling block to buying jewellery for someone else often comes from simple oversight—buying a piece, such as a ring or bracelet, that doesn’t fit the personality of the receiver.

“Try to understand the lifestyle of the person you’re buying for," Druckenmiller says. “Is she active? Does she use her hands for her job? That person might need something more lightweight, or made from more durable materials, than someone who (leads a more manicured) life."

Titanium, platinum, and diamond are options more rugged than, say, garnet, opal and gold.

If the person you’re buying for often wears big rings and chunky bracelets and necklaces, it’s a good bet she would like more in a similar vein. If she tends to wear only delicate stud earrings or a thin band around her ring finger, it’s likely she’s a minimalist.

Do a little research into history

Do your homework. It pays to know the history of jewellery, especially as it relates to fashion and culture. Before YSL and LaCroix were sending Byzantine-inspired costume jewels down the runway, Coco Chanel did it. And she did it best: Chanel’s baubles, brooches and chains inspired generations of fashion designers in the 1970s and 1980s. Her work carries more cachet, especially if previously owned by someone notable—a royal or a celebrity.

It’s very simple, Druckenmiller says: “Age adds to value. And provenance matters."