OP mentioned a bluish tint, this indicates a different surface layer. Possibly a nickel/tin mix which may have a very slight magnetic attraction, or even a silver plated alloy of silver/tin or even a zinc mix(tin/zinc being key to blue). Plating causes very silight weight differences, in the hundredths of a gram, usually well within planchet
Weight Tolerances. Most likely is a science"project", check YouTube for vids of DIY.
Edited by Crazyb0
11/10/2017 1:16 pm