I bought what looked like a nice AU/MS 1883 Alexander III Coronation commemorative rouble off of eBay about 2 years ago. When I held it in hand, it was immediately obvious that it was a fake, cast in nickel or some other base metal; the weight was wrong, too. Unfortunately, I didn't make pictures of it, but there was a perfectly straight horizontal casting mark on the obverse which extends from somewhere west of the middle all the way to the rim at 9 o'clock. For some reason (angle of lighting, probably) this casting mark was not noticeable in the eBay pictures. Anyway, I was able to return it for a refund. Several months later, I noticed that the same seller was trying to sell it again ... this time I recognized the casting mark.

Does anyone have a link to some pictures of this? There must be more of these around with such obvious marks as described.