The lighter end of the crayon
Purple Plum is one of the 16 shades in Crayola's Heads 'n Tails crayons, first sold in 2006. Each of those crayons has a different color at each end. Purple Plum is paired with Plump Purple, a bluer and darker shade. You can see all eight pairs in the list of Crayola crayon colors.
Beyond that crayon, the name has no history of its own. #9C51B6 is a screen estimate of the wax. It is brighter and pinker than the fruit color plum, and very close to purpureus.

