I didn't want to be rude and not post my update but it's not a happy one!
Now I know why I either buy new or live with what I find in the condition in which I find it!
I wouldn't have been bothered by the fading and condition of the collar (and leash) had my puppy been female but it didn't work for my little boy.
I decided to buy red Rit liquid and used it full strength letting it soak overnight. (I only tried to dye the collar; the leash is still the original color.)
Once the excess was rinsed and the water ran clear, I dried it, hoping I'd have a nice redder-than-it-looked collar.
The result was awful! The collar is still pink but now a slightly redder pink than it was, no longer matching the leash. And the leather seems to have absorbed the color unevenly, with some areas slightly pinker or redder than others.
Bottom line, I'm giving up and found another pre-owned BLACK collar! (And now the pink collar and pink leash aren't perfect matches to each other.)
I do appreciate the advice I received but rehab isn't my thing.