What I was referring to is the border around the pump plate itself, nothing to do with the decoration of the stations themselves, which is what I think you are questioning. There are blue and black border versions of the pump plates. The black versions were used on the west coast by General Petroleum, which operated in Washington, Oregon, Arizona, Nevada, and California. General Pet. was acquired by Socony in 1926, 5 years before the Socony and Vacuum company merger.
Always looking for Mobil items I don't already have!