What is the difference between fair market value and replacement value?

Fair market value is the price a willing buyer and a willing seller would likely agree on, with neither under pressure and both reasonably informed. It is usually based on what comparable items have actually sold for at auction or in the secondhand market.

Replacement value is what it would cost to buy a similar item new or from a retail source within a reasonable time. Because retail prices include dealer markups, replacement value is often noticeably higher than fair market value for the same piece.

Which one you need depends on the purpose. Insurance policies are commonly written on replacement value, while estate settlements and charitable donations usually call for fair market value. Tell the appraiser exactly why you need the report so they use the correct value definition from the start.