15 Loth (?) tazza

[AllSeasons]

I came across an item with interesting marks, and was wondering what they might mean. It appears to have a "15" stamped, along with another mark that I cannot decipher. Does the 15 mean 15 Loth? Or is it not solid silver at all, but silver-plated? In my understanding, 15 Loth is pretty rare, especially in earlier pieces, so I have my doubts. The other mark looks like it may be a crown of some sort. In any case, any insight would be appreciated. Thank you in advance.

[AG2012]

HI,
it must be tested to exclude French silver plate marks.
Regards