Unfortunately, there is no possible way any human being can definitively identify a strain based solely on a picture of a few dried buds.
On the other hand, I think you already have your answer.
If you think what you have is "blue dream" than its probably 99% likely that that is, in fact, what you have.
Blue dream is a "clone only" strain supposedly derived from two famous, award winning, and world-class parent strains, each bred by famous breeders: Mr. Nice Super Silver Haze, and the original DJ Short Blueberry.
I've never had the pleasure, but reportedly Blue Dream is just absolutely awesome in terms of potency, flavor, and quality of high. That's subjective, of course, but lots of people DO think this is the "best strain ever", so that part of your description fits.
"Blue dream" is also one of those strains that can turn purple, so your picture fits too.