I love the blue enamel religious medals.  They are just so beautiful, and the antique ones are often stunning.  This one is from the 1920's, and has lovely Art Deco slightly geometric styling.  It features both white and blue enamel, set in copper.  I did test the metal with a magnet, which didn't stick.  The color has darkened with age, and has wonderful patina - the aged look things get over time.  You can, of course, polish it, but that would remove the patina, which is a lot of the charm.  This little piece has been handled with love, for a really long number of years.  It is VERY small, just 5/8" tall.