Diamond Valley is a basin located in central Nevada in the western United States, between the Sulphur Spring Range and the Diamond Mountains. The valley is located almost entirely within Eureka County, but the northern end crosses into Elko County. The valley is up to 12 miles wide and over 45 miles long. The town of Eureka lies at the southern end of the valley, while the northern end is home to an alkali flat. Several small lakes are located in the western part of the valley near Sadler Brown Road.