I used Titan Violet Mica from New Directions in a soap I made a few weeks ago. It made a very dark purple (but not so dark as to be black). You can see the color on my YouTube channel NorthHillSoap- it's the Tiger Swirl video.
Kelly
I make a soap with bitter almond essential oil (rectified) and ground almonds that smells exactly like marzipan. I know you can get it from Voyageur Soap here in Canada- sorry I can't help with UK suppliers.