What Is This On My Coin?

Probably best to leave well enough alone.



to the CCF!

Silver turns black when exposed to sulfur. Coin collectors call this process "toning", but everyone else calls it "tarnish". This sulfur can come from numerous sources, including rubber, industrial pollution, cigarette smoke, bushfire smoke, kitchens where garlic and onions are prepared, certain types of wood, and coloured paper or cardboard.

Was the "envelope" yellow? Yellow paper is notorious for causing silver to tarnish. Or, they may have been stored in a cheap cardboard coin album, of the type that was popular back in the 1960s. In my experience, coins that are deeply toned only on the obverse (like this one is) have probably been sitting in cardboard albums for a decade or more.

As for removing the tarnish: sorry, but removing tarnish from silver is generally regarded as "bad cleaning". There are proprietary silver "dips" like Tarn Off, Lindner or E-Z-est that claim to safely remove tarnish from coins, but they're usually made of a sulfuric-acid-and-thiourea solution which will corrode the coin, slightly, leaving behind a dull, unappealing "cleaned" look.

Neither a coin dealer nor a collector will pay you extra for coins that have been badly cleaned. Most coin collectors prefer not to own heavily tarnished coins, but most of those same collectors would also prefer to own a tarnished coin rather than a cleaned one.


There is debate in the collecting community about how severely a tarnished coin ought to be downgraded. And while it may have minimal impact on the technical grade, it certainly has an impact on eye appeal, and therefore on resultant value.


Unlike tin pest (which can slowly spread spontaneously) or bronze disease (which only needs moisture to propagate), silver tarnish requires continuous exposure to atmospheric sulfur in order to "grow". Remove it from the sources of sulfur, or from the atmosphere entirely by placing it in a well-sealed 2x2 for example, and it will stop spreading.