JOEL - The seer stone was a small smooth brown stone about the size of an egg which Joseph Smith found in 1822 while digging a well for a man called Willard Chase. When Joseph received the Book of Mormon plates and the Urim & Thummim, evidence suggests that Joseph initially used the Urim and Thummim to translate but later would often use the seer stone because it was more compact and therefore more convenient to use. The Urim and Thummim are of course mentioned in the Bible as instruments that were used in conjunction with communications with God (Ex. 28:30; Lev. 8:8; Num. 27:21; Deut. 33:8; 1 Sam. 28:6; Ezra 2:63; Neh. 7:65).
The seer stone was no different than the Urim and Thumim Joseph Smith was given, which was constructed of two seer stones bound together in a silver bow. So there was no reason why Joseph could not use the single seer stone in the translation process the same as the Urim and Thummim.
God has in the past either provided such things or instructed man to build or use existing things as tools in manifesting His power and communication with man. There was for example, the rod of Aaron(Ex 7:9-10); the burning bush(Ex 3:2); the pillar of fire(Ex 13:21); the tabernacle of Moses(Ex 33:9); the ark of the covenant(Judg. 20:27); and the Liahona(Alma 37:38).

President Joseph Fielding Smith, with reference to the seer stone and the Urim and Thummim, has written: "We have been taught since the days of the Prophet that the Urim and Thummim were returned with the plates to the angel. We have no record of the Prophet having the Urim and Thummim after the organization of the Church. The statement has been made that the Urim and Thummim was on the altar in the Manti Temple when that building was dedicated. The Urim and Thummim so spoken of, however, was the seer stone which was in the possession of the Prophet Joseph Smith in early days. This seer stone is now in the possession of the Church." (Doctrines of Salvation, vol. 3, p. 225.)

The seer stone is kept in a safe place and is not available for public viewing as far as I know. I am not aware of any reports of the General Authorities using it recently. It's primary purpose was to aid Joseph Smith in translation of scripture, so there hasn't really been any reason to use it in our time.