The company expanded its offering through acquisitions, including Emerald Nuts, and Diamond of California Snacks and Nuts. By 1943, the association numbered 1300 growers who would bring truckloads of nuts to the plants.
The statewide association set standards for walnut production and marketing and established the ‘Diamond’ brand of walnuts.
In 1980 the walnut cooperative merged with other pioneer cooperatives, Sunsweet Prunes and SunMaid Raisin, to create the Sun-Diamond Corporation. By 2005, the walnut growers had jettisoned their cooperatives structure entirely, become an investor-owned corporation, Diamond Foods, and begun marketing a range of nuts and snacks under the Emerald label.
Diamond Foods became a publicly traded company in 2005. In 2008 the company acquired Pop Secret, microwave popcorn, from General Mills.
In 2010 the company acquired Kettle Foods makers of twenty-eight flavored potato and tortilla chips. Kettle Brand Potato Chips, by Kettle Foods, developed its brand from a homebased business in 1980 into the leading brand for “all natural” potato chips.