If it has no hallmarkings to indicate the silver content, or marks such as "Sterling", "925" ( Sterling is 92.5% silver) then it is highly unlikely it's Sterling silver. If you feel that it is silver, you can have it tested, most jewelers should be able to do this for you.
Re: Antique Ashtray
If it has no hallmarkings to indicate the silver content, or marks such as "Sterling", "925" ( Sterling is 92.5% silver) then it is highly unlikely it's Sterling silver. If you feel that it is silver, you can have it tested, most jewelers should be able to do this for you.