Mark - You can get that same look with what you have on hand.
I use only Alumilite dyes and powders, and have gotten those color mixes consistantly. You've already struck on the need to keep a log. I started keeping a log with my first casting, it makes it a lot easier to reproduce the casting if you like it.
The one you've got pictured looks like a three color mix;
1) Dark blue base
2) Light blue w/pearl
3) Purple(equal red & blue liquid) w/a small amount of pearl
When I see a casting I like I try to break it down to how many colors it has, what color is the base and what color(s) are the accent(s). Then you'll need to break down the volumes of each. For a three color casting like you got a picture of the base looks like 2/3 of the over all pour, leaving the accents to about 1/3 each, of the over all volume. Then after you've poured the three colors into the mold you'll need to "swirl" them with a stick or something. Of course that swirling is a lot easier in a flat mold like those castings came from.
I hope this helps.
Happy turning