Ok so I recently came into possesion of a few gold coins, one of them being the 1947 50 peso, I right away noticed that on the eagle side there was a discoloration that looked alot like rust with a silverish center. My question is if this devalues the coin, or if I should clean it etc. Thanks for any info.
It sounds like a copper spot. Some people like gold coins with copper spots, because they say it shows that the coin has original surfaces. Others don't like them. Charlie Edited to add: Cleaning a coin will almost assuredly devalue it.
to CoinTalk guy. P l e a s e use the search button at the top of the page and read some of the multitude of prior threads on cleaning. Bottom line, unless your coin has some kind of corrosion that is eating away coin metal leave it alone. Gold doesn't normally corrode, especially .900 pure gold like the Mexican 1947 50 Peso, but your description could conceivably be of a coin with an uneven alloy mix, resulting in a noticeable copper spot. Please post a picture of the coin so some of the real gold experts can eyeball it. If it were mine, and had the problem you describe, I would certainly consider sending it to NCS for professional conservation because of its value, but I would never, ever, even think of trying to "clean" it myself.
