Here is a dealer ad for the 1952 Philharmonic TV.
Notice in the list of features: "Simply adaptable to color TV."
http://www.tvhistory.tv/1952-Philharmonic-Ad.JPG
Of course, nothing to do w/the 1954 15" color set, but shows that color was still a selling point in 1952.
Ad courtesy of Tom Genova's TV History site
-Steve D.