“Owsley invested in a professional pill press and soon he started dyeing his tablets a different color each time he turned out a new shipment. Although there was no difference between the tablets (each contained a carefully measured 250 micrograms), street folklore ascribed specific qualities to every color: red was said to be exceptionally mellow, green was edgy, and blue was the perfect compromise.”

—Martin A. Lee & Bruce Shlain, Acid Dreams: The Complete Social History of LSD, 1985.