I have also done the density/gravity test and it was 10.8 something instead of 10. 5 ??
So it's about 0.5% heavy. How do you know that your scale is that accurate?
They either over-poured when casting the bar (unlikely) or Your bar is not 100% pure silver. or Morningfox is right and your scale is inaccurate.
The purity should be stamped on the bar. If its .999 (which is typical) then its suppose to be 99.9% pure silver with only a trace of any other material. Even at only .9 purity (90%) you would need an awful heavy element (like Uranium) to get that extra 1.5 g Your density measurement makes me suspect your instruments are not accurate. If someone wanted to defraud you they would add a substantial amount of cheap metal like copper or lead or iron. Trouble with that is that only Lead is heavier then Silver. So adding Copper or Iron would give you a smaller density then silver. Adding Lead will give you a density higher then Silver ,but even 100% Lead would be smaller then your measured value of 10.8. Lead has a density of 10.66 g/cc and Silver 10.49 g/cc. Density of Uranium is 19.05 g/cc. I suggest you bring it to a school and have them weigh it on an accurate balance in Chemistry Lab.
