Diamond is an unincorporated community in Harney County, Oregon, United States. Diamond is west of Oregon Route 205 and south of Malheur Lake, 52 miles (84 km) south-southeast of Burns by highway. Its post office is assigned ZIP code 97722.

Harney County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 7,495, making it the sixth-least populous county in Oregon. The county seat is Burns. Established in 1889, the county is named in honor of William S. Harney, a military officer of the period, who was involved in the Pig War and popular in the Pacific Northwest.