How graders detect cleaning
Original coins have luster made of microscopic flow lines radiating from the center — cleaning shears or scratches those lines, and the damage is unmistakable under a grading light. Rotating the coin reveals hairlines (fine parallel scratches), flat or glossy patches where luster should cartwheel, and unnaturally bright surfaces on a coin whose wear says it should be darker.
Old cleanings that have re-toned still show the disturbance beneath the new color. Harsh chemical dips leave silver looking stripped and lifeless; polishing leaves a hard shine no mint ever produced. Graders review thousands of coins a week — subtlety rarely wins.
What a details grade means
When PCGS or NGC judges a coin cleaned, it returns it in a holder labeled with the problem — for example, UNC Details, Cleaned — instead of a numeric grade. The coin is certified genuine and its wear level noted, but it is excluded from regular grade pricing and registry sets.
Details holders are honest packaging, not punishment: they let problem coins trade transparently. Many collectors happily buy details key dates as affordable set fillers.
The size of the discount
Discounts scale with the harshness of the cleaning and the rarity of the coin. Lightly cleaned scarce coins might bring roughly 20–40% less than problem-free examples; harshly cleaned or polished common coins can lose half or more of their value, sometimes falling to metal value.
Rarity cushions the blow — a details 1916-D Mercury dime still commands strong money because demand outstrips the supply of problem-free examples. Common material has no such cushion: a polished common Morgan is just damaged silver.
Check before you buy or sell with CoinVault Pro
Pricing a coin correctly means knowing which market it belongs to — problem-free or details. Scan coins with CoinVault Pro for an AI grade estimate and live sold-price comps, and be honest about surfaces when comparing: unnaturally bright coins should be compared against cleaned sales, not gem money.
Cataloging inherited or purchased coins in the collection manager with clear photos also creates a record of surfaces as-received — useful if questions ever arise later.