Green; Chromium is the usual element claimed to be responsible for the attractive green colour of emerald. However, some emeralds from Colombia, Russia, Lake Manyara(Tanzania), Afghanistan, Nigeria, Zambia, and Carnaiba(Brazil) are characterised by unusually low contents of chromium. Indeed, some of these emeralds contain up to about 0.3% V₂O₃, which also may contribute to their emerald green colour(Brown, 1984; Platonov et al., 1984; Wood and Nassau, 1968). The large variation of iron content in emeralds is due to the possibility of incorporating iron, either as Fe²⁺ and or Fe³⁺, in different sites in the beryl lattice. Indeed specimens of bluish green Zambian emerald were quite distinct from other emeralds analysed as they have the highest iron content but low concentrations of chromium.

Both colombian emeralds and the synthetic emerald had less FeO than all other emeralds. In addition, the Colombian Emeralds contained considerable amounts of CuO. Bluish green Zambian emerald and emeralds from Carnaiba(Brazil) both had lower chromium contents than emerald from other locations. Some emeralds from Afghanistan and Brazil were slightly enriched in iron as well as vanadium.