Some thoughts from a mineral collector. There is considerable variety in naturally occurring diamonds. Colors, such as yellow, green, brown, black and famously a few blue and pink ones. Plus many crystal forms (Cubic, Octahedral, Dodecahedral, Tetrahedral, Trapezohedral, Tetrahexahedral,Trisoctahedral, Hexoctahedral, and some triangular Macle forms). An appeal of natural diamonds to some mineral collectors is the interest their unique crystal forms. These are expensive and tiny: a niche that I don't have in my collection. However, I did purchase a large cluster of what I think consists Moissanite crystals, not transparent; it looks like some failed industrial experiment.