To me it looks like a Treviri (or Treveri) coin of about 60-30 BC, Scheers 230-231. The obverse is pictured upside down. It is a stylized (celticized) eye looking to the right. The Treveri gave their name to the city of Trier, and yes, they lived around Luxemburg. This coin, if it's real (and gold) could be quite valuable, but probably less than the auction prices you may find (because the word POTTINA is outside of the flan). Correct me if I'm wrong.
Hello, I'm a member since an hour ago. I'm from the Netherlands and restarted collecting after a long pause. I have a broad interest and knowledge of coins, but I pinned down collecting to 300 BC-800 AD, and from India to Britain and everything between. But especially Dark Ages and Migration period. I just bought this coin, from Vakhu Deva, a king of Zabulistan, about 700 AD. In my eyes, it's a real beauty.