Ali bin al-Mubark al-Hna'iy علي بن المبارك الهنائي · The Book of Adornment

"The Messenger of Allah said: 'The best things with which you can change gray hair are Henna and Katam.'"

"The Prophet of Allah took hold of some silk in his right hand and some gold in his left, then he said: 'These two are forbidden for the males of my Ummah.'"

The Prophet's ring was made of silver and its stone (Fass) was made of silver too.