According to Millet and McConkie, the phrase "I will prepare unto my servant Gazelem, a stone" (Alma 37:23) may well be a play on words. Is Gazelem the seer stone or the servant? It is difficult to tell from the passage and depends very much on the placement of a comma in the sentence. Perhaps it could refer to both. It is interesting to note that when Jesus called Simon Peter to the ministry he said: "Thou art Simon the son of Jona: thou shalt be called Cephas, which is, by interpretation, a seer, or a stone" (JST, John 1:42). Though this name or title of Gazelem may be used in regard to any seer who utilizes seer stones, it seems in this instance to be a direct reference to Joseph Smith the Prophet. [Joseph Fielding McConkie and Robert L. Millet, Doctrinal Commentary on the Book of Mormon, vol. 3, p. 278]
“I Will Prepare Unto My Servant Gazelem”
According to Roy Weldon, there have been stories, traditions, etc., of a chocolate-colored stone used by Joseph Smith in translating. Inasmuch as this work is concerned with claims in the Book of Mormon, and there is no mention of a chocolate-colored stone in either the Book of Mormon or the Doctrine and Covenants, we offer only brief references.
James Lancaster in an article in the Saint's Herald, "By the Gift and Power of God," November 15, 1962, deals extensively with the chocolate stone theory.
F. Edward Butterworth has prepared a paper, "The Mystery of Urim and Thummim," in which he has done considerable research regarding the Urim and Thummim in ancient Israel. He has a paragraph entitled "The Chocolate-Colored Stone," in which he states:
Besides the two stones on the shoulders of the high priest, there were twelve stones in the breastplate. These twelve stones representing the twelve tribes of Israel were arranged in the breastplate in the order of the birth of Jacob's twelve sons. In this case the eleventh stone represented Joseph the eleventh of Jacob's twelve sons, and the elder son of Rachel. Oddly enough the eleventh stone in the breastplate was described by Josephus as made of "onyx," a dark or chocolate-colored stone. As might be expected, since the Book of Mormon is the history of a remnant of Joseph's tribe, this was the color of the seer stone used by Joseph Smith, Jr., in his translation.
[Roy E. Weldon, Book of Mormon Deeps, Vol. III, pp. 339-340]