David Whitmer notes that Joseph was presented with a chocolate-colored seer stone to substitute the Urim and Thummim.

By fervent prayer and by otherwise humbling himself, the prophet, however, again found favor, and was presented with a strange, oval-shaped, chocolate-colored stone, about the size of an egg, only more flat, which, it was promised would serve the same purpose as the missing Urim and Thummim (the latter was a pair of transparent stones set in a bow-shaped frame and very much resembled a pair of spectacles). With this stone all of the present Book of Mormon was translated. It is the only one of these relics which is not in the possession of the Whitmers. For years Oliver Cowdery surrounded it with care and solicitude, but at his death, Old Phineas Young, a brother of Brigham Young, and an old-time and once intimate friend of the Cowdery family, came out from Salt Lake City, and during his visit he contrived to get the stone from its hiding place through a little deceptive sophistry, expended upon the grief-stricken widow. When he returned to Utah he carried it in triumph to the apostles of Brigham Young's "lion house."See Full