At the age of 15, Perkin entered the Royal College of Chemistry in London. It was there, just a few years later, that he discovered the first synthetic dye. Since antiquity, purple garments had been a mark of royalty, as natural purple dyes had to be extracted from mollusks or insects and were thus quite expensive. The lab-created dye made Perkin a wealthy man. In 1906, the chemist was knighted. At the time of his discovery, he had had been trying to create a synthetic version of what?