MAC Vio-lit is a cool purple with a sparkle finish that is limited edition and retails for $21.00. In comparison, Natasha Denona Amethyst (141M) is a cool purple with a sparkle finish that is discontinued and retails for $29.00.
Natasha Denona Amethyst (141M) is 80% similar — it is less shimmery, darker, warmer.