Of course it's real. I remember seeing them for sale on Fiverr and Freelancer a long time ago. Heck, I just got a review from a company trying to sell reviews on Yelp about a week ago, take a look:
I didn't even have to report this review, Yelp automatically found and deleted it. The reviews that they would leave will also be deleted, most likely. Yelp and Google are smart enough to figure it out.
New advertising option:
A review of your product or service posted by a Sterling Sky employee. This will also be shared on the Sterling Sky & LSF Twitter accounts, our Facebook group, LinkedIn, and both newsletters.