In Europe a silver alloy of .835 is very common, as is .925. You
stated that you couldn’t test, which would help solve the question.
Maybe the base metal is .835 silver with a 14k coating which is very
common as well (Vermeil), although mostly used with yellow gold.
Another explanation could be that someone messed up during marking
the piece. There are many examples of strange essay-office errors,
which make the study of these so interesting.
The .835 for white gold is not common, .833 however is used at
One of those nice mysteries.