"Royal Blue" wasn't a thing until the Python was introduced in 1955...at least not by name. Various models could and did receive the high polish blue prior to that. It depends on the model...how it was spec'd out and the person doing the polishing and assembly.
Some of the finest Colts and Smith & Wessons were produced in the 1920s and '30s. The finishes they had were spectacular...especially in the '30s during the Depression. Production was down and the companies were able to keep the best finishers and assemblers as they were happy to still be employed...and with fewer orders they had the time to really do some fine work.
But...to the question...not all Colt autos got the Royal Blue treatment. The Gold Cups normally did. The others not so much. During that time period there were some spectacular nickel plated guns being produced...just don't see them as often due to lower numbers.