See the 3rd picture I just uploaded. It is stamped "STERLING" and "925." Good question though. I'm kind of new to this whole thing and didn't know about the marks.
Invest in a test kit for silver and or gold....not everything that is marked 925 or sterling is authentic....not saying your item isn't real...just that I've sold for years on ebay and etsy and have run across many things that were fake....OR that were sterling but not marked. (925 = sterling......higher end pieces use "Sterling" ) In the meantime you can tell if something is real 925 by holding a magnet near it....Real sterling silver is not attracted to a magnet.
Thanks for the tips! I held it up to a magnet just to make sure and there was no attraction. So between that and it's two stamps, I think it's a safe bet to say this is authentic sterling.