What is a jewel worth? This is the question an auction house must ask when determining an estimate. On the surface, the estimate represents a calculated projection. In truth, the estimate is a mood-setter; it can stir competitive bidding, create urgency, or offer rare opportunities to acquire something spectacular. And as jewelers note, these compelling numbers, whether strategic or sincere, can ripple through the trade long after the hammer falls.
Most purchases of precious stones and jewelry happen behind closed doors, leaving collectors and connoisseurs in the dark about true values. Auctions, however, offer a transparent platform where extraordinary gems and heirloom jewels achieve their prices on the global stage. They don’t just set records; they set benchmarks, serving as vital barometers of value in an opaque industry.
“At its core, an auction estimate is an open-market valuation,” says Kate Flitcroft, co-head of jewelry at UK-based auction house Bonhams. “It is a service we offer to clients to give an indication of what their jewel might fetch on the open market. Estimates are carefully considered, with more than one specialist consulted. For fine jewels, we operate as a global team to research comparable pieces sold recently at auction, considering market dynamics. Accurate estimates encourage collectors to register, and once bidding starts, competition between them can drive the final price far beyond presale expectations. Our estimates are set with this in mind — high enough to signal the quality of each work while [still] remaining attractive.”
Benoît Repellin, worldwide head of jewelry at Phillips, echoes that sentiment. “Our approach combines expertise with thorough research to position estimates strategically [so they] encourage competitive bidding. The starting point of an auction is key; each bid builds momentum, and a well-judged estimate plays a central role in driving this process, ultimately leading to strong results.”
How low can it go?
While some estimates may seem to undervalue a piece, there is a rationale behind setting them low, says antique-jewelry expert Brenda Kang.
“First, it encourages more buyers to enter the auction market,” explains the founder and owner of Singapore-based Revival Jewels, who worked with Christie’s for 15 years, including as regional representative of Singapore and China. “Second, it offers a positive outcome: Post-sale press announcements will always mention that a jewel sold beyond its estimate. And finally, some auction houses [receive] a performance commission — it may be an extra 2% on top of the standard commission — if the bidding crosses the estimate.”
Ultimately, says Kang, “an auction house’s priority is to ensure that its client’s jewelry is sold…. Both parties trust that the item will find its price in the market.” However, “clients should also be aware that accepting low reserves and estimates carries risk: If luck isn’t on your side, your items could sell well below market value.”
Sixth-generation gem and jewelry dealer Melissa Wolfgang Amenc affirms that setting the expected price low can be beneficial. The director of Geneva-based Golay Fils & Stahl recalls one piece “that had a ridiculously low estimate. It was being sold by a provincial auction house. It eventually sold for around 300% more than the estimate. Anyone in the trade looking at that stone knew the estimate made little sense. Did it devalue the jewel? Absolutely not. Did it encourage bidding? For sure. Had the auction house estimated the jewel’s value just under what it eventually sold for, it would have discouraged bidding, as most would have thought that they didn’t have a chance. Hope walks a fine line between faith and folly.”
Reserve judgements
Auction houses are also more frequently offering pieces without a minimum reserve price, as this, too, makes them more likely to sell. However, such a move can be a gamble, according to John Glajz, founder of Glajz-THG in Singapore — and the risk is even higher when the consignor is a jewelry dealer rather than a private owner.
“Auctions are probably the best outlet for private individuals to sell merchandise, and PR and marketing have raised the profile of auction houses in the public domain,” says Glajz, whose company specializes in rare fancy-color diamonds. In some cases, private jewelry owners have no costs to offset, he explains, “because they’ve either inherited an item or were given the jewel.” As such, there’s no need for a reserve price or a higher consignment value to protect them from selling at a loss.
However, members of the trade are under more pressure, he continues, “because we all have an acquisition cost with little room to maneuver.” If the achieved price exceeds what the consignor paid for the item, having no reserve pays off, but if not, the seller has no recourse.
The importance of accuracy
Two or three decades ago, the main bidders at jewelry auctions would be trade professionals with in-depth knowledge of their craft. However, the launch of online auction platforms has enabled almost anyone with a credit card to bid on a jewel, and the vintage auction segment has exploded. The result? More auctions throughout the year, and more bids at those auctions, leading to higher prices.
“Over the past two decades, the market has evolved significantly, with clients becoming increasingly informed — whether through greater access to data, expert advisers, or enhanced transparency,” comments Repellin. This means “every estimate must be carefully considered, reflecting current market conditions accurately.”
That’s not always how it turns out, though, according to third-generation dealer Gilles Zalulyan. “In my 30 years of working in this segment, I have seen jewels sold extremely cheap, and some sold for amounts far exceeding their real value,” relates the cofounder of antique-jewelry seller Palais Royal, which has operations in Hong Kong and Paris. “Auction houses often protect themselves by offering limited guarantees — typically only what’s stated in bold type.”
The language that auction houses use can be unclear to buyers. For example, seeing names like “Cartier” or “Fabergé” in the description might lead one to assume a jewel is authentic. However, if the catalog says “in the style of,” it usually means the piece resembles the designer’s work and era but has not been confirmed as theirs. Similarly, “bearing marks of” may indicate that the jewel has later-added marks and is not from the original workshop. Beyond these issues, some major auction houses only guarantee authenticity for five years from the auction date — something many buyers don’t realize.
Rather than using vague phrasing, Zalulyan maintains, auction houses should clearly confirm or disclaim the authenticity of their pieces.
Of course, that’s not the only area where mistakes can occur, he continues. “Misjudging the value or significance of a piece is also a critical error. One of my clients purchased a Boucheron bracelet at the 2022 Magnificent Jewels auction by Sotheby’s, but the fact that the bracelet’s origin was as part of a choker — with one part now missing — was relegated to the end of the condition report. This, I believe, is not in keeping with the spirit of our commitment as an industry to straightforward communication. Essential information should be easily accessible, ensuring that our clients can make informed decisions without unnecessary effort.”
Main image: Sotheby’s takes bids in November 2024 for an 18th-century diamond tassel necklace, which beat its upper estimate of CHF 2.2 million ($2.6 million) to sell for CHF 4.3 million ($5.1 million). (Sotheby’s)
