Emerald is a suburb in the Greater Melbourne area, Victoria, Australia, 44 km south-east from Melbourne's central business district, just inside the urban area. Its local government areas are the Shires of Cardinia and Yarra Ranges. At the 2011 Census, Emerald had a population of 6,813.
Emerald also includes Cardinia Reservoir, Melbourne's second largest reservoir.
The Emerald Post Office opened on 22 December 1899.
Emerald is known for the Emerald Lake (Lake Treganowan). The lake offers barbecue facilities, children's playgrounds, a pool, paddle boats, walking tracks, fishing, Environment Centre, model railway, café and a railway station for Puffing Billy.
The Puffing Billy Railway is a heritage steam operated railway opened in 1900, which runs between Belgrave and Gembrook, now recreating the heyday in the 1920s of this narrow-gauge line. It has three stations within Emerald—at Emerald, Nobelius and Lakeside, with Nobelius only being a "Stops if required" station. Also, Nobelius Siding is located between Emerald and Nobelius stations which is only stopped at for functions, or the regular "Dinner Train" at the former Nobelius Nurseries Packing Shed adjacent to the siding.