I couldn't tell you. As the others have said, Suuntos aren't exactly the kind of watch that people would usually bother counterfeiting. Having said that though, stranger things have happened - and in color too. Since it appears, however, that you just registered in order to ask this question - I'll tell you the usual advice:
Shop the seller
Aside from some context-less photos of some random watch, what do you know about the seller? Is the seller suspicious in any way? Do they have a track record of happy customers? Do they have any sort of history anywhere that you can verify? Are they asking you to do something stupid like send them a wire-transfer or a PayPal gift?
If the seller appears to be legitimate than the watch probably is too. If the seller is trash, it doesn't matter if the watch in those particular photographs is legit.