From emerald. The Queensland town takes its name from the emerald and other precious stone deposits in the area and from the pastoral run Emerald Downs, a name chosen circa 1860 by pastoralist Peter Fitzallan MacDonald. It is unclear if emeralds were found in or around Emerald. The given name is a modern coinage from the name of the gemstone, representing a vernacular form of Esmeralda.

Etymology: Wiktionary (CC-BY-SA)