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In the Latter Day Saint movement, the Urim and Thummim (also called Interpreters) were a set of seer stones bound by silver bows into a set of spectacles, that founder Joseph Smith, Jr. said he found on the hill Cumorah with the golden plates.
In 1823, Smith said that an angel Moroni told him of the existence, with the plates, of "two stones in silver bows" fastened to a breastplate, which the angel called the Urim and Thummim and which he said God had prepared for translating the plates. His mother, Lucy Mack Smith, described them as crystal-like "two smooth three-cornered diamonds."...