You'd have to provide a lot more info. The weight, a picture, etc. There are people on here who can give you an informed opinion. I'm not one of them. Generally, unless you obtained it from a trusted dealer or got it from someone who did, odds are it's a fake.
Consider it a $7 lesson learned - you might consider buying a nice bezel and chain (for more than $7) and wearing it as a daily reminder to do your homework before buying suspect coins