Imperial Purple (also known as Tyrian Purple) is a deep red colour resulting from a dye extracted from the marine snail Haustellum brandaris. Only kings, noblemen, high-ranking church officials and judges were able to afford this rare and expensive luxury, and in the Roman Republic, there were strict regulations, based on the wearer's rank and status, on how much of this purple an article of clothing could contain. Restrictions tightened when the emperor came to rule, as emperors were distinguished by wearing togae purpurae, purple togas; hence the phrase "to don the purple" for the assumption of imperial dignity
As the Roman Empire weakened, and other dyes such as lichen purple and madder became more widely available and less expensive, the use of Tyrian purple declined. It ceased as an industry in 1453 with the conquer of Constantinople by the Ottoman Turks (1). Throughout the Renaissance, the dye became even more uncommon. The so-called “Cardinal's Purple,” was really the first luxury dye of the Renaissance- scarlet extracted from the kermes insect.