Tyrian Purple (also known as Imperial Purple) is a deep red colour resulting from a dye extracted from the Murex, a marine snail Haustellum brandaris. Pliny the Elder describes the production process in the 1st century AD. It was used by the Phoenicians, highly prized by the Romans, and was used to a lesser extent in the Middle Ages. It is thought to be the dye used in ancient times to make tzitzit, Jewish prayer shawls. 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.