Ken Hurst and Rocketman gave it to you right. I have no idea what the dark engraving, light background could be; some engravers have experimented with masking and gritblasting specific areas of an engraving, with quite striking results.

Here is a Ruger with a French gray finish, done by rust bluing then dipping in a tank of blue remover (Brownell's Steel-White):

[url="http://www.hunt101.com/?p=444484&c=500&z=1"][/url]

Bill