Purple is a colour that combines blue and red. Purple is used to represent royalty. It is a sign of power, nobility, luxury, and ambition. It shows wealth and extravagance. It is thought as a royal colour because in Roman times, there was only one way to make the colour purple, which the Romans called purpura.
They used one or two species of the sea snails called Murex, which produced the dye in a gland. These shellfish came from the Mediterranean Sea. Each snail produced only tiny amounts, so not much of it was made, and it was very expensive. The process of making the dye was long, difficult and expensive. Thousands of the tiny snails had to be found, their shells cracked, the snail removed. The snails were left to soak, then a tiny gland was removed and the juice extracted and put in a basin, which was placed in the sunlight. There a remarkable transformation took place. In the sunlight the juice turned white, then yellow-green, then green, then violet, then a red which turned darker and darker. The process had to be stopped at exactly the right time to obtain the desired colour, which could range from a bright crimson to a dark purple, the colour of dried blood. The exact hue varied between crimson and violet, but it was always rich, bright and lasting.
Therefore purple was only worn by the rich: it was mainly the colour of kings, nobles, priests and magistrates. Naturally, the richest and most famous people in the country were the Roman emperors, who they were the few ones able to wear purple.