What is this brooch?

[emelie]

Hello there!
Can anyone tell me anything about this brooch? I think it looks celtic but I'm from Sweden so it could be something else. Is it old or new? I can't find any marks or stamps. It's quite heavy (16 grams). I don't know what metal it is either but it doesn't have a smell.

 

[VRBeauty]

The rough finish on the back, combined with the fact that the stone appears to be glued in place rather than prong-set or bezel-set, suggests that this is a nice piece of costume jewelry. I agree that it looks like a Celtic-inspired design.