I have a Graflex RB, Series D, a 4X5 SLR, all original save for a back from the 1950s (so you can use modern sheet, roll, and Polaroid backs) and, as far as I know, it works. The black leather is all original and it has a focal plane shutter (T, 1/10 through 1/1000 sec). Lens is a No. 33 Kodak Anastigmat 7-1/2" f 4.5.

Company is listed as “The Folmer Graflex Corporation”, Rochester, NY, USA.

The patent dates on the bottom plate range from 16 Dec 1902 to 6 May 1913. The metal is finished in black paint. It looks as if it has a faint bluish cast.

Anyone have an idea as to its rarity and value? (I have photos of the camera that I can e-mail if you're interested.)

Looking down <a href=http://graflex.org/graflex-products-list.html> this page</a> and over looking the typos you'll find it made from 1929 to 1945.
The link to the RB on line manual in the heading for this section will tell you how to operate it.
Value depends on a lot of things and its anyone's guess as to how many are still in existance and useable.
Charles