Welcome to CT, I am no expert in Greek coins but the guys and gals that can advise will need to know the diameter in mm and the weight of the coin. They will be along shortly to advise. Looking forward to seeing some of your other ancients Mr-Devils.
Welcome to CT @Mr-Devils If you confirm the weight of your coin being 13,8 grams, then it has to be fake An actual owl tetradrachm is about 17 grams (and very constant from an example to another) Sorry about that Q
Good morning @Mr-Devils and welcome to the forum. Would the Devils happen to be blue? Unfortunately I have to agree with the folks above who have condemned the coin as a fake.
It's not authentic. Sorry about that. If it's silver it is worth at least melt value. BTW, welcome to CT @Mr-Devils