Carl, here is a scan of the back side of the Sands Regent bar. This bar is one ounce. As you can see in the scan, someone cleaned this bar and wiped it with a maybe cotton cloth, notice the fine scratches.These do come up on eBay. Not very often though. Below is a link to one on eBay. Way over priced and has been on eBay of at least a year.

https://www.ebay.com/itm/The-Sands-Regent-Hotel-Casino-SANDS-1-Silver-Art-Bar-P1797/332441960871?hash=item4d6715c1a7:g:xysAAOSwySlaAv4W:sc:USPSFirstClass!93602!US!-1:rk:1:pf:0