Premium-on-Premium
Premium-on-Premium
The compounded-fee structure that occasionally surfaces in secondary auction and intermediated trade
Premium-on-premium is the auction and trade term for a fee structure in which a buyer's premium is calculated on a hammer price that already includes another premium or fee, with the result that the buyer pays a premium on a base that is not the actual hammer figure. The pattern is rare in major gemstone auctions, where buyer's premiums are clearly stated as a percentage of the hammer price and additional fees are itemised separately. The term most often appears in discussions of multi-stage sales, intermediated transactions, and secondary auction structures where successive margins can compound in a manner not transparent to buyers who do not read the small print.
The standard auction model
The standard buyer's premium structure at the major coloured-stone, diamond, and jewellery auction houses — Christie's, Sotheby's, Phillips, Bonhams, Heritage — is straightforward in form even when the percentages vary. The hammer price is the figure at which the lot is knocked down. The buyer's premium is a percentage of the hammer price, typically tiered with reducing percentages above set thresholds. Sales tax and any applicable resale royalties or import duties are added to the total, but they are calculated on a transparent base.
Under this standard model, premium-on-premium does not occur. The buyer's premium is calculated once, on a single defined base, and the buyer's total cost is the sum of the hammer plus the premium plus any taxes and duties. Reputable auction houses publish the formula in their conditions of sale and in the buyer's prospectus.
Where premium-on-premium does occur
The term has historically applied in three contexts. First, in some online resale and intermediated platforms, a percentage fee is added to a quoted price that already includes a previous markup, with the second percentage calculated on the marked-up base rather than on the underlying transaction value. Second, in certain trade-show and dealer-network sales, successive margin layers are applied as a stone moves through intermediaries, each calculated as a percentage of the price received from the prior intermediary. Third, in poorly-structured secondary auctions and consignment formats, fees can be layered without clear separation, and the cumulative effect mimics premium-on-premium even when no single fee is explicitly so structured.
For buyers, the operational risk is straightforward. A 10 per cent fee on top of a price that already carries a 10 per cent margin is not equivalent to a 20 per cent total markup; the compounding effect produces a higher total than addition would suggest. The difference is small in any single transaction but accumulates meaningfully across multiple stages.
How to read auction terms
The defensive practice for any buyer in a non-standard auction or intermediated sale is to demand a clear written statement of how the buyer's total is calculated. Ask which figure the buyer's premium applies to. Ask what other fees are added and on what base. Ask whether sales tax applies to the hammer alone, to the hammer plus premium, or to the full purchase total — practice varies by jurisdiction. Reputable houses provide all of this information without prompting; non-standard sellers frequently do not, and the absence of a clear fee structure is itself an indicator of risk.
In the modern major-house market
The major auction houses do not engage in premium-on-premium pricing in the modern era. Buyer's premiums are tiered, transparent, and calculated on the hammer price — not on a marked-up base. Where premium-on-premium concerns arise in the modern market, they tend to be at the edges of the trade: online platforms with non-standard fee structures, multi-stage consignment sales, and certain offshore secondary auction formats. The term remains in trade parlance principally as a cautionary reference for buyers approaching unfamiliar sale formats.
In the trade
For dealers and serious collectors, the premium-on-premium concept is most useful as a framework for analysing total cost in any non-standard transaction. The presence of layered fees, opaque base calculations, or unclear sequence of premium applications is an indicator that the apparent price is not the actual cost. A buyer who calculates the total in advance — including all fees on the correct bases — has a clear picture of what the lot will cost and can compare it to alternative purchases on a like-for-like basis.