That could be anything. Fake, genuine, ancient, made last week.
The quality looks the part, but you really need to supply as much written and photographic detail as possible if you want to stand any chance of an answer here.
May I suggest you send three or four photos (from various angles, with an open tape measure or a well known coin in frame for scale) to a big auction house. Also tell them the weight.
If interested, they would no doubt pass it on to their resident expert in such items.