...but can you call them "silver alloy"?
No, you cannot say it is a silver alloy. Disclaimer I am not a
lawyer but you can give them a trademarked name like "Pinkle" then
in your advertising you can say it is an alloy of x percent silver,
y percent copper, z percent zinc or like Tiffany is doing with
Rubedo to say it is
an alloy containing gold, copper, silver although they may be
playing a little fast and loose by not giving percentages and
leaving off the smaller percentage components in that alloy like
zinc. But in any case if you mention precious metal content you
must list all the alloying elements every time you mention the
precious metal content.
For a lot more info on this go to the JVC website
and look at their quick reference and essential guides on precious
metal jewelry. They are clearly written and well worth reading if
you sell jewelry in the US.
James Binnion Metal Arts