I need to clarify something.
In many articles, I've talked about the fact that pieces made of sterling should be marked as sterling. I should have emphasized that I've been talking about pieces made by established silver companies that have produced many sterling pieces over the years - companies such as Gorham, Reed & Barton, Wallace and the like.
For pieces made in the United States, in order to mark a piece as "sterling", it must contain at least 92.5% silver. But there is no law that says such a piece must be marked as sterling.
It's a fact that many sterling pieces have not been marked as such. Many of these were handmade, especially in the area of custom jewelry. Unfortunately, this means that the absence of marks is not clarifying enough to say that a piece is not sterling. But, fortunately for me, the sterling pieces I deal with, i.e., mass-produced pieces, are virtually all marked as sterling.