Most don’t fade within a week. My hair is fuchsia at the moment, but I’ve had every color of the rainbow at some point or another. Shades of blue and green fade the fastest and are the most finicky to work with. You can expect a blue or green to fade within 2 weeks and it never fades to a nice looking color. Pinks and purples last the 2nd longest in my experience depending on the brand you use. Manic panic or ion work the best, there is another brand that Sallys sells (n’rage maybe, idk, it comes in what looks like a lotion bottle and smells like bubblegum). avoid Beyond the Zone if lasting color is your goal. They use to make good dye but they recently reformulated and now they suck. Pink and purple will last about a month or longer if you put the remaining dye into your shampoo and conditioner it will help keep the color. After a month or 2 your roots will need to be re dyed. Btw, you will have to lighten your hair first because these none of these colors or brands will stick to natural hair! Reds last the longest and are a huge bitch to remove, the good thing is that any brand of red will hold fantastically. Yellow and oranges are hard for almost anyone to pull off.