I searched the world over for historically accurate solid-brass furniture ring pulls, and finally, I gave up and made my own. 

The base or post portion of these pulls is 3/8" tall and 1/4" in diameter. The ring is 1/2" in diameter. Be sure to drill pilot holes prior to installing: 1/8" for softwood, 9/64" for hardwood and horn. I like to put a drop of glue on the threads first.