The GIA D–Z scale, near-colourless sweet spots, and how mounting metal affects face-up hue.
Colour grading measures body colour on the D→Z continuum; D–F read icy, G–J can still photograph white if cut is commanding.
Tone strip (conceptual)
- Yellow gold mountings camouflage faint warmth; platinum demands higher colour tiers for the same “white” subjective read.
- Hue vs saturation: fluorescence can cool I–K face-up daylight while leaving the grade unchanged.
- Always compare melee side stones when ordering halos—they should not out-whiten the hero diamond.
