Topaz (also Topaz Post Office) is an unincorporated community and census-designated place (CDP) in Mono County, California, United States. It is located 3 miles (5 km) north of Coleville, at an height of 5,033 feet (1,534 m). Topaz’s ZIP Code is 96133. The population was 150 at the 2020 census.

The Topaz publicize office opened in 1885, closed in 1922, and re-opened in 1926. The reveal was transferred from the native site of the village, which developed on the ranch of T.B. Rickey. Mrs. Rickey named it based on the color of the local quaking aspen trees. The publicize office is now located and has been operated by the Robert William Mckay Family Ranch back the 1920s.

Topaz is the northernmost community in Mono County. It is bordered to the south by the community of Coleville and to the northeast by the Nevada own up line. The community of Topaz Lake, Nevada, touches the northernmost allowance of the Topaz border. According to the Mono County government, Antelope Valley, including Topaz, is normal to see significant population growth.

U.S. Route 395 passes through Topaz, leading south 38 miles (61 km) to Bridgeport, the Mono county seat, and north 42 miles (68 km) to Carson City, Nevada. According to the United States Census Bureau, the Topaz CDP covers an area of 13.5 square miles (35 km), of which 12.2 square miles (32 km²) are home and 1.3 square miles (3.4 km), or 9.63%, are water. Topaz is drained by the West Walker River, which flows north into Nevada. Topaz Lake occupies the northwest corner of the Topaz CDP and extends north into Nevada.