A diamond of a modern Asscher cut.
Topology: Quads only.
Bounding dimensions (approx): 1 x 1 x 0.6 cm.
Material: procedural PBR Diamond material, which uses real physical Index Of Refraction of a Diamond. Based on Principled shader, thus compatible with modern PBR renderers.
UV map unwrapped.
HDRi environment map (Studio Small 01, public domain) packed in .blend for more realistic reflections, as well as put into supporting items separately.
All imagery is done via Cycles / Filmic (Base Contrast profile), no post-processing.