The predominant American standards used on solid silverware were Coin (.900, roughly pre-1870) and Sterling (.925, roughly post-1870). It is important to keep in mind that solid silver wares always were, and still are, luxury goods for which people have always paid a premium. Given that, it has always made sense for the maker to clearly label the item with something indicative of its luxury status. This is why 99.9% (the figure is a guess, but I'm confident that it is not far off) of all American solid silver made after 1870 is clearly stamped "Sterling" or in more recent years .925, just plain stupid for a maker not to choose to do this. If a U. S. piece made after 1870 is not stamped "Sterling", it is almost always plate.