MAC Evil Twin is a very cool-toned, medium-dark purple with a pearl finish. It is a limited edition eyeliner that retails for $16.00 and contains 0.01 oz.
Evil Twin ($16.00 for 0.01 oz.) is described as a "blue purple." It's a brightened, medium-dark cool-toned violet with a pearly finish. It had fairly good pigmentation in a single pass (and that's even better for purple eyeliner, since most are weak in regards to pigmentation!), and it was buildable to opaque color after two layers. The color wore well for eight hours before fading on me. Sephora Collection Eccentric Diva (P, $9.00) is warmer. Tarina Tarantino Amethyst Android (P, $15.00) is similar. See comparison swatches / view dupes.