Originally Posted by Alk8944

The black color of typical S&W anodizing is created literally by adding dye to the anodizing bath. This is why anodizing is available in virtually any color that may be desired. As with virtually all dyes it can fade and sun bleach. often when this happens the anodizing can take on a purplish color, just like black fabrics do. This is one of the possibilities for the color you see.