Dura Coat white, with an overcoating of 'bicycle blue' metal paint from Home Depot.
I did experimentation on some bar steel flats and looked at different colors and mixes. Also looked at the different blue formulations being used by gunsmiths today. Visited some local smiths (and or their customers) and looked at how their blue jobs turned out. None of the commonly available finishes these days give the old Colt Blue I sometimes see traces of on older pistols. Instead they are all shades of black. Since that old Colt Blue was a fired blue with a gas or wood flame under a mix of crushed bone and charcoal before the pieces were tempered, or confined to just small parts. I have occasionally duplicated that tint by coating steel bolts with oil and powdered bone and lighting it with a torch. However re-tempering heated steel for a gun is not a do-it-yourself project, so doing that to an already existent pistol was too problematic. Besides, the fire blue evaporates or changes to a blackish gray as it oxidizes over the decades. [The belgium version seen on old pistols and shotguns from the mid 1800s was a similar process.] Colt switched to a mostly chemical only blue sometime around 1904 to 1913 or so. [Some debate exists as to the date depending on which gun, or whose book you read. A big fire helped push the change.] Still, as I looked at the original Colt blue found under the ejection rod housing of one of my generation 1 Colt SAAs, and some photos of some of the earlier Colts in which the blue color is still visible, I decided the Colt 1903 should have that color all over (except for the pins and safety as a contrast). Experimentations on steel strips with different paint and dura-coat sprays and mixes of soon followed. The metal was prepped with Jasco then the duracoat was applied a day later. I am pleased with the blue that was selected.