Special symbols and numbers are engraved at the back of the stones at a certain time of the year for only one day and night when the moon is in Scorpio (April 8).
On this day, a special prayer called Sharaf al-Shams or Sharaf-e Shams, which consists of five major names of God, is engraved on ring stones, usually yellow agate, in order to solve the problems of the wearer.
Wearing agate is believed to cure insomnia and those who wear agate believe they get long life, family happiness, and prosperity. It is also said that agate can create joy in the heart, and is good for eyesight.
Here are the photos of engraving God’s names on the stone in Iran retrieved from ISNA:
