Good timing bro! I just finished up on a Nirvana - Blue Mystic grow and I noticed three pheno's, two of which were completely different while two shared very similar characteristics.
Pheno # 1 Dark blue with light purple hues, medium to tall growth, med to large calyx. Extremely healthy looking.
Pheno # 2 Dark purple, almost black. Same aroma and stickiness as pheno #1 but short and stout, smaller flowers. Some buds look like Blue Cheese!
Pehno # 3 Light blue hues with creamy white and orange through most flowers. Slight minty aroma while still being fruity like the other two phenos. Med to large growth, very healthy.
Below is the thread I posted pics of Pheno 1 & 2. In the blurrier picture look at the bud behind the center flower. Theres a little sticking out the top right hand side. That's a good look at the darker almost black bud.
http://www.marijuanapassion.com/forum/showthread.php?t=35882
I was going to get AK48 from Nirvana but I may try another site with lower prices and that is giving Mazar X Afghan freebies away. I can get two strains (20 beans) and an extra 5 Mazar X Afgan beans for the same price I can get 10 beans of AK48 from Nirvana. I'm not knocking those fellas at all because I am grateful for my Blue Mystics beans, but I think I'll check out the competition and see what shakes out.