Looking at My book "Colt An American Legend by R.L Wilson" The serial Number of your Colt Police Positive indicates it was manufactured in late 1930. Chuck L_ Dothan Al
These were made by the Iver Johnson company as a second, less expensive line of revolvers from about 1910 to 1935. If the serial number (under the grips) does not have a letter prefix, it is one of the early production guns. Commonly finished in nickel plate, late production guns were sometimes blued. Values about $90-$150, depending on condition. They wer made in a hammered and hammerless version.