How do I know if my coach purse is real?

I was just given a coach purse. My mom got it from someone else. It did have the brown bag in it. But I have tried to look up my serial number and am having no luck. From the looks of the label it is a real looking number. It is a smaller blue tote type bag. The only thing that is throwing me off is the C's are in different colors and different sizes. my coach number is m04k-5659. I have read that the 5659 is a fake number unless its on a scribble tote. But I don't know if that is what I have as all the pictures I find are all in different colors and mine is all done in blues.