Hi Ed:
An inquiry was made about these tokens being marked "Sterling"
a few years back to clarify exactly what the silver content was.
It seems that Franklin Mint said these were "Proof Like Solid Silver",
which qualified them as almost pure silver, therefor a .999 silver
content even though they were only stamped "Sterling".
In many countries, ratings anywhere from .875 - .999 are also just
labeled as sterling. I had early European silver that was marked .875,
but was considered to be sterling on the metals markets .....