Yeah, highly skeptical at this. I wonder if they forgot a "copper" in there somewhere. I wouldn't be surprised if it was copper core plated with silver/gold instead of a silver core plated with gold that this seems to suggest.
It is possible tho I mean how much is a silver jewelry chain they cost less than this and probably have more silver. The problem is every example of pure silver and silver gold plated wire we have seen on ebay has been ridicuous 10 dollars per foot for a single wire in a very small diameter this is multiwire, terminated, and ready to go. Also you would think with wire that nice they would use better terminating jacks as these look like plain aluminum. At least use pailiccs or something. Terminators I say give it away the most as not being real occ silver wire but you never know for sure until you cut it apart and dip it in some titrated marker chemical.