It is not prescribed to write Aayat al-Kursiy or the name of Allaah on pieces of gold that are to be worn, because that is a kind of disrespect. It may also be an imitation of the Jews and Christians who hang up or wear things that they revere, such as the cross etc.
There is a concession allowing writing names on rings, even if the name includes the name of Allaah, such as Abd-Allaah or ‘Abd al-Rahmaan. Similarly there is nothing wrong with writing useful words on a ring even if they include the name of Allaah, such as al-hamdu Lillah (praise be to Allaah), tawakkaltu ‘ala Allaah (I put my trust in Allaah) etc. Many such reports have been narrated from the Sahaabah and Taabi’een. Some examples have been mentioned in the answer to question no 68805