Great question.

There are some that are clad as in no silver content. Those do not have a .999 represented on them either on the brass ring or the silver insert. With exception the Hard Rock in Las Vegas. Theirs does not say .999 however they in fact are all .999 silver.

As for those that do say .999 on them. They are either .60 of an ounce or .50. They were made both ways in weights. The earlier strikes were .60 while the later strikes before they switched to clad were .50.

Hope this helps

Dennis
SS-094
R-8000