Who's gun would that be, Roy? Dave (Researcher) already knew his was a Black Diamond, as did h d hawgr. The post by Valman noted engraving of a dog on a lockplate, and case colors, which pretty much rules it out as a Black Diamond #55, as the catalog says it is a mid-priced gun with line engraving, and a black finish.
Which gun are you talking about?
Best,
Ted