It's the Colt Open Top pocket model; they made some 114,200 from 1871 to 1877 for .22 Short and Long, (not Long Rifle). The standard guns had nickel plated (or, rarely, silver) frames, with blued or nickel plated barrels. The grips were varnished walnut. The little guns sold pretty well, but Colt could not compete against cheap "suicide special" guns selling for much less.
Now the problem. While Colt could and did turn out guns on special order, I think yours has been modified after market, and rather recently. The gun probably had flaking nickel plating, so someone buffed the plating off entirely and then reblued the barrel and cylinder with modern caustic blue and gold plated the frame. It makes a spectacular piece, but it is not original and the collector value has been effectively destroyed. I suspect, but would have to see the gun to know, that the grips are not real ivory.
Value, IMHO, around $400, maybe more if someone likes the glitz.