Natural Red Diamonds

Red diamonds share pink's colour mechanism — plastic deformation of the crystal lattice under mantle stress — but require a degree of lattice distortion so extreme that a pure red grade from a gemological laboratory is a geological improbability. Fewer than thirty gem-quality examples are reliably documented, making red the rarest natural diamond colour by a substantial margin. Saturation is the defining criterion; even modestly sized Fancy Red diamonds trade as singular events in the market.