Bob, sterling silver is 92.5% pure silver and 7.5% copper as an alloy. Coin silver is 80% silver and the rest usually copper. I would expect that "low grade silver" may really be considered anywhere from 80%-75% pure silver (or less) with copper making up the rest. In this range, this is the reason why many silver fittings on old Moro/PI stuff have a pinkish hue to them - it's the copper content.
One day when I grow up (and have money
) I'll have one of these too.
