An English auction — also termed an ascending auction — is the open, competitive bidding format in which an auctioneer solicits progressively higher offers from participants until no further bid is forthcoming, at which point the highest bidder secures the lot. It is the dominant format employed by the world's principal jewellery auction houses, including Sotheby's, Christie's, Bonhams, and Phillips, and its transparency makes it particularly well suited to unique, high-value, or otherwise difficult-to-price objects such as signed jewels, important gemstones, and historic pieces. The format's defining characteristic — that all bids are public and each supersedes the last — produces genuine price discovery in real time, a quality that sealed-bid and descending formats cannot replicate.

Mechanics and Structure

A sale conducted under the English auction format begins with the auctioneer announcing an opening bid, which may be set at or slightly below the lot's published low estimate. Bidders — present in the saleroom, on the telephone, or participating via an approved online platform — then compete by offering successively higher sums. The auctioneer controls the pace and the bid increments, which are standardised intervals by which each new offer must exceed the previous one. Increments are not arbitrary: the major houses publish increment tables that scale with lot value, so a lot bidding in the low thousands advances in steps of, say, £200 or $200, while a lot contesting in the millions may advance in steps of £50,000 or more. These tables are publicly available in each house's conditions of sale.

Bidding continues until only one active bidder remains. The auctioneer signals the close — traditionally with a fall of the hammer — and the final bid becomes the hammer price. To this sum the buyer adds a buyer's premium, a percentage charged by the auction house that typically ranges from roughly 12.5 to 26 per cent on a sliding scale, depending on the hammer price tier and the house's current fee structure. The total paid by the buyer — hammer price plus premium plus applicable taxes — is the total purchase price.

Reserves, Estimates, and the Chandelier

Most lots in a major jewellery sale carry a reserve, a confidential minimum price agreed between the consignor and the auction house below which the lot will not be sold. If bidding fails to reach the reserve, the auctioneer passes the lot — it is said to be bought in. Published pre-sale estimates reflect the house's expectation of where competitive bidding will settle, but they are advisory rather than binding; exceptional stones regularly sell far above their high estimates when two or more determined bidders are present.

A subtlety of the English auction format is the practice of taking bids off the chandelier (or off the wall): the auctioneer may open bidding with a fictitious bid on behalf of the house in order to advance the price toward the reserve without revealing its level. This is legal and disclosed in conditions of sale, though it can be confusing to inexperienced bidders. Once the reserve is met, all subsequent bids must come from real participants.

Why the English Format Suits Gemstones and Jewellery

The English auction is especially effective for objects whose value is subjective, condition-dependent, or driven by provenance — precisely the attributes that characterise important gemstones and signed jewellery. A Kashmir sapphire of exceptional colour, a Cartier Art Deco bracelet, or a diamond with a notable ownership history may have no reliable comparable sale; the open competitive process allows the market to establish value in the moment, incorporating information that no single appraiser could fully anticipate.

The format also rewards research and preparation. A bidder who has examined a stone in person during the pre-sale viewing, reviewed the gemological report, and studied comparable results is positioned to bid with conviction. Conversely, the public nature of the bidding means that the enthusiasm — or restraint — of other participants conveys information about perceived quality, which can influence undecided bidders in the room.

Telephone and Online Bidding

The English auction format has adapted readily to remote participation. Telephone bidding, in which a specialist at the saleroom relays bids on behalf of an absent client, has been standard practice at the major houses for decades and is particularly common for high-value lots where the buyer wishes to remain anonymous or cannot travel. Online bidding platforms — proprietary systems operated by each house, as well as aggregators such as Invaluable — extend the format's reach further, allowing real-time participation from any jurisdiction. The mechanics remain identical: bids ascend, the hammer falls, the highest bidder wins.

It is worth noting that absentee bids (also called commission bids or left bids) are accommodated within the English format: a bidder submits a maximum figure in advance, and the house's specialist or automated system executes bids on their behalf up to that ceiling, competing against live bidders as if in the room. The system is designed to secure the lot at the lowest possible price consistent with the absentee bid winning — it will not automatically bid to the maximum if competition ceases at a lower level.

Distinction from Other Auction Formats

The English auction is most usefully understood in contrast to two alternative formats occasionally encountered in the trade. In a Dutch auction (descending-price auction), the auctioneer begins at a high price and lowers it until a bidder accepts; this format is efficient for commodities sold in volume but poorly suited to unique objects. In a sealed-bid auction, all participants submit offers simultaneously without knowledge of competing bids; the highest offer wins, but there is no opportunity for competitive escalation. Neither format generates the transparent, iterative price discovery that makes the English auction the standard for fine jewellery and gemstones.

Buyer's Due Diligence

Participation in an English auction for gemstones and jewellery carries responsibilities that the format itself does not mitigate. Lots are sold as described in the catalogue, and while the major houses make reasonable efforts to ensure accuracy, condition reports and gemological certificates should be reviewed critically. Independent laboratory reports — from institutions such as the Gemmological Institute of America (GIA), Gübelin Gem Lab, or SSEF — are increasingly standard for significant stones and provide objective documentation of species, origin, and treatment status. Bidders are strongly advised to attend pre-sale viewings, examine lots under magnification where permitted, and consult a qualified gemmologist before bidding on any stone of material value. The competitive dynamics of an English auction can create pressure to bid quickly; preparation is the most reliable defence against overpaying.

Further Reading

• GIA: Buying Gemstones at Auction
• Christie's Conditions of Sale
• Sotheby's Conditions of Business