Amethyst (#9966CC) is a medium, moderately saturated purple hue. Amethyst is a medium purple named after the violet quartz gemstone.
In RGB it is made of 153 red, 102 green and 204 blue. Its HSL hue angle is 270° with 50% saturation and 60% lightness, while its perceptual OKLCH lightness is 61% with a chroma of 0.156. For print, a starting CMYK mix is 25% cyan, 50% magenta, 0% yellow and 20% black.
As a text color on white, Amethyst has a contrast ratio of 4.1:1, which passes AA only for large text and UI parts. On black it reaches 5.13:1 and passes AA for normal text. If you use Amethyst as a background, put black (or very dark) text on it. The APCA lightness contrast is Lc 36 for black text and Lc -73 for white text.
Its perceptual complement is #6D9100, close to olive. Colors that look most similar are orchid, plum, royal blue. It looks fairly similar to people with red-green color blindness (ΔE 11), so its meaning mostly survives.