Could you actually tell us what it is, not just the name of it?
I'm going to guess that it changes the appearance of your hair somehow, which is not possible. You could cast the spell all you want, with or without a ring, but it would only leave you wondering why it didn't work.
Aphrodite, goddess of beauty i ask that you enchant this ring/watch (put the ring on the photo)so that when it is worn my hair will start to look more and more like the woman's in this photo. i ask that it is the same color as this lock of hair, (put the lock of hair on the photo)and that the hair will remain even after the ring/watch is removed, i offer this blood as a sacrifice to thee(wipe the blood on the ring). aphrodite i ask you let this be