Just a rough ID: That's an Indian fanam from Mysore, probably 19th century, and worth about 5-10% (on a good day!) of what the seller is asking...
I swear ,unless it's a recognizable western coin, (Greek, Roman, Byzantine), sellers put it up as "celtic".
Well, hey, there was just that Coin Week article from the other thread about Celtic coins. They were gold with squiggles, this is gold with squiggles, so there you go!
Could be either a weird style Krishnaraja Wodeyar fanam, or else something older from Vijayanagar. Definitely not celtic and likely worth $50, tops.
Unscrupulous eBay sellers have been offering common Indian fanams as "Celtic" for as long as I can remember. Caveat emptor.