Sunday School lesson in 1934 describes briefly how Joseph Smith used seer stones.

As near as we can learn, the translation of the plates was about as follows: A curtain was stretched between Oliver and the Prophet to prevent the writer or anyone else from seeing the records. Joseph worked on one side, and his scribe on the other. When the Prophet was ready to begin reading, he took the plates from the small "Red Morocco trunk," as described by the mother, then produced the Urim and Thummim, which was made of two transparent stones set in silver bows. At other times, he used the Seer Stone. With this aid the Prophet looked at the strange characters upon the records, studying and praying. Then as soon as he was able to read the meaning, he quoted it to the writer, knowing through the testimony of the Spirit when it was done correctly. Thus were the lines and pages of the Book of Mromon brought out of a strange and curious writing into English, easy to read.