Appreciate the words, Erisian and sorry for the belated reply; I do work full time on weekends so just got home a few minutes ago. Anyway, I did used Voronoi Stipper (too lazy to find that thread, but we've had many here at GIMPChat already) to create the 12000 dots. To turn those dots into marbles is the "secret sauce" that is to varied to really explain, but does start with G'MIC's Local Orientation preset (set to .05 smoothness) and then blurred and that result set to Grain Merge over the dots. That's most of the dimensional effect. As for the gloss, I used so many things (and PS filters) which again I do at the seat of my pants so to speak, but there's many ways to add gloss and reflections. Once I make the marbles glossing, I create a convolution layer (original photo I duplicate, run Bilateral smoothing and set that result to Grain Extract, I merge down and set the result to Grain Merge; that resulting layer is the convolution layer) to make the image look more like the original photo; only do this step on the dots. I then add reflections/drop shadows on the Onyx/granite background. I know; a bit vague; also I've used many other tricks in the past so it's all about how lazy I am as to what I end up doing.