well I don't know for sure., last night i was thinking about it and take a look up at the top left in the large glass ring. see how all the colors are blended together the yellow and green are interlaced etc. that comes from the number of times i whirl it around in the 3d. .. Check my fractals pdn style in my gallery. the method I use is how I always start my work. must be in that somehow. just the right blend then luminosity is applied. I've been trying to track when I get glass but it just seems to be different for each color blend and amount of each color. so far!