I just picked this up from my local Norris store the ladies were very knowledgeable on the difference between the blue and violet, I chose violet for the desired look I wanted and it was spot on I used this product with two different brand developers I didn’t see any difference with those, I added in NAK STRUCTURE COMPLEX NO.1 to help strengthen my hair so less chance of frying and the entire combination was perfect it’s so soft and I haven’t even needed conditioner yet (as I’m debating putting pink in my hair) my hair was prelightened prior but very porous before using these products combined.