The Prophet ﷺ used to wear the stone of his ring facing the inside of his palm.
حدثنا أبو بكر بن أبي شيبة حدثنا سفيان بن عيينة عن أيوب بن موسى عن نافع
أن النبي ﷺ كان يجعل فص خاتمه مما يلي كفه
Related by Muslim in "Clothing and Adornment," chapter on the Prophet's ﷺ wearing a silver ring... hadith 55/2091, from Ibn Abu Shayba, with this wording.