Jerry, legend has it that in the celluloid building of a knife making operation, all the different colored scraps of celluloid were swept up at the end of the day for one last batch of handle material. Hence the name for these confetti-like handles, every color of the rainbow. "End of Day". Yes, of course one of these may have turned out abalone-like. Regardless of the legend, knife companies (or the extremely rare celluloid factory supplying them) make these on purpose.
Note that I wrote above 'celluloid building'. The material is very flammable and explosive, so it was done away from the other operations. At least one factory's cell building has a hinged roof, so the inevitable explosive force would go up and out without taking the entire building down. This is the same material used in old movie film, and that is/was a danger there.
Let me make this answer even longer: In the great old movie... was it 'The Front Page'??? a reporter needed to make a flash for his camera quickly. He gathered all the celluloid collars from his comrades and ignited them as he pushed the shutter button. Unlikely, but illustrative.
Hope this suffices. Phil