Colorado Breweries History: Keystone Brewery Besides the eponymous Coors ® line of beers, Coors produces the Keystone line of beer under their own name. Various subsidiaries of Coors brew Blue Moon, Killian's, Saranac, and Zima®. Main Brews: 1) Keystone Premium is a high quality lager and member of the Keystone Family. Keystone Premium is 4.4% alcohol by volume and has 122 calories per 12-ounce serving. 2) Introduced in 1989, Keystone Light is a refreshing light lager that is Always Smooth, Never Bitter™. Keystone Light is 4.2% alcohol by volume and has 100 calories per 12-ounce serving.