Hi badmikey.
That's a hell of a question.

I own an original black copper stingray but don't have any stingray clones. I would guess it would be fairly difficult to tell without side by side comparison if you are unfamiliar with the type of machining quality you get on originals vs clones.
A 1:1 clone will have minor physical differences I am sure but as to what those would be..... you could try youtube and look for a comparison video.
BUT I suspect the short answer is if you paid under 100$ for it it's a clone.
That's all I got...hope it helps
