This mark appeared here or somewhere else before, but I didn't have any of the wrenches then and cannot remember who it represented. The wrenches are all thin like tappet wrenches and are not plated.
From Alloy Artifacts site
http://alloy-artifacts.org/trademarks-and-logos.html
X-Circle Duro Metal Products Stylized "DC" denoting Duro-Chrome
Much thanks Mad!
The Circle DC was used on both Duro and Indestro tools during WW2 production.
-Don