News item: Rust discovered on Bank of Russia .999 gold coins

pendragon1998

'Rust discovered on Bank of Russia .999 gold coins

Improper alloying process leading to copper spots?


"It would be embarrassing if it were discovered that not only is the bank diluting the gold content once received with oxidizable materials, but subsequently passing it off for 999 proof precious metal."

Um...what is .999 gold if not also .001 'oxidizable materials'? lol I think they meant more than 0.001.

Lancastercoin

There is no alloying process for fine gold. Spots on .999 coins are caused by foreign matter from the dies, handling, packaging, etc; and is strictly a surface effect (i.e. totally removable). Not saying there is or isn't anything funny going on at the Russian mint, but this spotting happens on certain fine gold coins from every major mint.

SaorAlba

Check out the 1940's dated Mexican coins sometime, they are famous for copper spots. I have seen copper spots on some of the 1980's dated AGE's too. Given the lower fineness on those coins you have to imagine it is coming from inside the coin. With the Russian coins, I would not be surprised to hear that Goznak doesn't have clean enough processes to keep the coins from being contaminated with foreign substances after the blanks are made. Similarly on some of the .999 Chinese gold I have seen surface spots that are likely post blank contamination from foreign substances.