NumiHow to compare coin auction prices using sold lots
Find sales that match your coin and compare the same price basis, with the date, original currency, and lot link attached.
Start with the actual sale
Look for a published result tied to an original lot page. Save the auction house, lot number, date, price, and currency together. A dealer’s asking price or an opening bid can tell you what someone offered the piece for. It can’t tell you what a buyer paid.
When the lot includes several pieces, keep it separate from sales of individual coins. Splitting the price evenly across a group assumes that every piece contributed the same value.
Compare the things that drove the price
Match the type, denomination, metal, and reference first. Then compare condition, strike, centering, surface issues, and the legibility of the design. Two coins that share a reference can draw very different bids. A documented pedigree can matter too, especially if it is unusual for that type.
Save a few relevant results across different sales. If one result sits far apart, record the reason you included it or kept it out. An old result or a grade mismatch can still be useful context when it’s clearly labeled.
Worked example using two published Trajan denarius sales
Classical Numismatic Group reported a USD 475 hammer for Electronic Auction 477, lot 472, on September 23, 2020. The lot was RIC II 189, a Rome-mint Trajan denarius with seated Pax and a kneeling figure, cataloged as Good VF. The lot states an 18% buyer’s fee. Applying that fee gives USD 560.50 before any taxes, shipping, or other charges.
Electronic Auction 615, lot 654, sold for a USD 275 hammer on August 12, 2026. This Rome-mint Trajan denarius was RIC II 293 with Trajan’s Column, cataloged as Near VF with scratches. At the 20% fee stated for that auction, the price including premium was USD 330 before other charges.
Both records belong in a broad Trajan denarius search. For a valuation, keep them in separate groups by reference and use each as context until you find additional sales of the same type and similar condition. The dates are also far apart. These two observations alone cannot isolate the effect of the reverse type or condition on the price.
Put the prices on the same basis
Check whether the result is the hammer price or includes the buyer’s premium. For example, a hypothetical $100 hammer with a 20% premium is $120 before tax and shipping. Check the terms for the specific auction when the result page doesn’t say how the price was recorded.
Keep the original currency and sale date. If you convert currencies, record the rate, its date, and its source as well. The European Central Bank publishes euro reference rates for information. Treat these as a consistent research conversion and keep an actual card or dealer exchange rate separately when you know it.