Unusually, this adjustable wrench has company name on both sides of the handle, "upside down" on this side.
in 1908 the Diamond Calk Horseshoe company started making horseshoes and calks (traction inserts for horseshoes) in Duluth, Minnesota. By the 1920s, with less market for horseshoes they had branched out into railway supplies and wrenches. The business was successful and they continued in the tool business, adding pliers of different types.
The company remained a family business longer than most, being sold to Triangle in 1981. See Alloy-Artifacts for an extensive company history.