Sorry Snake, I didn't see your response to my question until just now.
Yes, semi-gloss black was factory on my 69 Cali built Dart. Same color/shade as the blackout that is present in the front wheel well.
The bolt/nut that holds the 2 pieces together is black phosphate plated.
The bumper to bracket hardware is bright zinc plated, except for the lockwasher which is black plate as well.
One note: If you purchase the bumper bolt kits from the popular vendors, they supply a flange nut for the application whereas the factory used a regular trim hex nut along with a flat & lock washer.
Hope this helps some!
Stay warm buddy.
George