I finally made my own lamp and was extremely disappointed that the Lava was transparent.
I tried using Vybar 260 (a polymer that candlemakers use to increase opacity in candles) and that didn't work either.
I'm going to try titanium dioxide next as this is what is used to give things like paint, and sunscreen lotion it's white colour.
This thread is from 2010, so I hope there are some new suggestions since then. Thanks