If you purchased Crucial RAM open a Support ticket and give them your Ram's Serial Number. Crucial will know if that is a valid Serial Number or not.
Plus I really haven't personally heard of fake RAM Memory modules unless you purchased it from a website like Ebay that sells a lot of fake Merchandise.
You can also use a Ram identification type software that will show what type of RAM Memory your module uses and then check with the manufacturer's website to see if it is the same or not.