I have only used it in the base I know fits all bottles. I'll try it in my other 2 tomorrow and let you know. I have a clear/White in the worst base I have at the moment and it fits very snug, strange. Guess it only needs a tine amount of difference and it wont fit.
It's great in the day but, I bet it isn't much cop at night. I wouldn't have thought it would let out much light and that's what I personally like about most lava lamp colours, they let out light and light up the wax when the lights are low etc.
It seems indeed to be a rather deep dark purple but I guess in broad day light it might and should made it !
One thing tho I don't understand is that color combo isn't showing on mathmos website, UK or any else one. Is it a custom bottle made on demand ?
Just to let everyone know LavaWorlds black wax lamps are just heavily dosed with violet. There is no actual black colored wax, even LavaWorlds black waxes will look purple if you look close enough. Jonny Magma (when he was around) had the same problem and said if they did black wax it will simply be heavy doses of violet. There is no actual black colorant.