Should I clean old coins before I sell them?

No. Cleaning is the most common way people accidentally lower the value of a coin. Collectors want the original surface, including natural toning and color that built up over decades. Polishing, scrubbing, dipping in chemicals, or even rubbing with a cloth leaves tiny scratches and an unnatural shine that experienced buyers spot right away.

A cleaned coin is often valued well below an uncleaned one in the same condition, and grading services note cleaning on the holder. For common coins that are worth only their silver or face value, cleaning makes little difference, but it can badly hurt a scarce date, and you may not know which ones those are yet.

If coins are dirty, leave them alone. Handle them by the edges, not the faces, since fingerprints can leave marks on the surface. Keep them in non-PVC holders or the albums they came in. Let a coin dealer or appraiser look at them as they are. If a coin truly needs conservation, that should be done by a professional service, not at home.