When I helped my friend with her Amethyst cosplay, I found the exact color your's talking about! OvO
It's Snazaroo Lilac and it's great for long, all-day cons (as long as you seal with Ben Nye Final Seal, of course) It's super easy to apply, is water-based so it doesn't stain clothes, and is SUPER cheap (8 dollars for a huge cake of the stuff!) It goes on a little red at first, but with a couple of layers will make it a much smoother, creamier color. Adding a little Snazaroo Light Grey to the mix really makes it the perfect color though, if you're willing to get it. (I think it's worth it) Also, making arm socks might really help you, if you're willing to put in the time! That way you don't have to worry about your arms, just your face!
Experience: Sollux from Homestuck, helping my friend with her Amethyst from Steven Universe.