Very Rare Small-Sized Stoneware Mug with Cobalt Spot Decoration, attributed to Charles F. Decker's Keystone Pottery, Chucky Valley, TN origin, circa 1880-1905, finely-potted mug with stepped base, tooled shoulder, and applied handle, decorated around the shoulder with two rows of cobalt spots. Additional spot decoration spanning the length of the handle. Heavy cobalt highlight to lower handle terminal. Upper handle terminal decorated with an inverted U-shaped stroke, reminiscent of the splayed petals of tulips found on much of the Decker family's ware. Comparison of this mug with the designs and forms of a few extremely rare signed examples by William Decker, son of Charles Decker, Sr., indicate this mug may be by his hand. William is the short-statured potter with a neck injury visible on the far left of the iconic Decker Pottery photograph. Excellent, as-made condition with a salt drip to interior. H 3 1/4".