Natural Blue Diamonds

Blue diamonds owe their colour to trace boron in the crystal lattice — at fractions of a part per million — absorbing red, orange, and yellow wavelengths and transmitting blue; these Type IIb stones account for fewer than 0.1 per cent of all natural diamonds and are the only gem diamonds that conduct electricity. Saturation governs value absolutely: fewer than 1 per cent of blues submitted to GIA reach Fancy Vivid, and a grey secondary hue reduces price substantially at equivalent intensity.