Violets are a mid-tier caste, though they are mentioned to be as rare as Whites. They are the creative class, the artists, musicians, and performers of society. They are also news anchors and appear to work with technology and dabble in genetic engineering. They are given drugs (pills) to increase their output.
Violets are mentioned to be "as rare as whites."
Notable violets include:
Mickey mentions to Darrow that he grew up in something called "The Grove," where he was given psychadelics and made to create what he saw in his nightmares. The Grove is quite probably the colony where Violets are raised.
Darrow sees that their Sigil resembles an amethyst mask in smoke, but they always change.
In a Society where technology has turned some fields of science into an art form, the Violet Carvers are the craftsmen that alter the physiology of creatures, for example, the Oracles of Octavia au Lune, Lorn au Arcos's Icarus, tigerlynxes, the giant sea creature in the Citadel, they were all Carved. The griffins used by Golds to convince the Obsidians that they are Gods are also the result of carving.
They also Carve Colors, for example, Fitchner's wife had her fallopian tubes modified, Darrow was Carved into an Iron Gold, and Evey was given wings. Pinks were mentioned to be Carved into mermaids as well, and at Darrow's Triumph, there were also drakes and zebracores. They are seen on Europa, the moon where Lorn and his family reside.