Pronunciation

KROH-muh-for

The atomic or molecular structural feature responsible for a material’s color. In gem-quality color-change diaspore, the chromophores are trace iron (Fe³⁺) and chromium (Cr³⁺) substituting into the aluminum site of the diaspore lattice. Their combined absorption spectrum produces transmission windows in the green and red regions, which is the physical basis of the alexandrite effect.