They were traditionally worn as a part of the Hoshen (sacred breastplate) attached to the Ephod (sacred vest), though their exact composition is never directly described, as the stones were kept hidden from view.
The place where God resides is a great Urim and Thummim.
This earth, in its sanctified and immortal state, will be made like unto crystal and will be a Urim and Thummim to the inhabitants who dwell thereon, whereby all things pertaining to an inferior kingdom, or all kingdoms of a lower order, will be manifest to those who dwell on it; and this earth will be Christ’s.
Then the white stone mentioned in Revelation 2:17, will become a Urim and Thummim to each individual who receives one, whereby things pertaining to a higher order of kingdoms will be made known;
And a white stone is given to each of those who come into the celestial kingdom, whereon is a new name written, which no man knoweth save he that receiveth it. The new name is the key word.
Yale coat of arms, showing the phrase “Urim and Thummim” written in Hebrew
The phrase “Urim and Thummim” is usually translated as “lights and perfections” or “revelations and truth” — and its Latin equivalent, Lux et Veritas, is the motto of several universities, including Yale, which many of my ancestors attended.
In Paolo Coehlo’s 1988 novel, The Alchemist, the Urim and Thummim are black and white fortune-telling stones that Melchizedek gives to Santiago, with black indicating “yes” and white indicating “no” — but Santiago never uses the stones, having promised himself to “make his own decisions.”
This brief ritual uses three “linestones” from Linestone as a localized Urim and Thummim — placed above the eyes and taken in the mouth to receive a vision of what is to come.
As the film concludes, the image recedes into the void.