anas bin malik (ra) says:

"rasulullah (saas) had a ring made of silver and its (inlaid) gem was also of silver."108

when the prophet (saas) wanted to write to the leaders of foreign states, he ordered a seal-ring to be made.

"rasullullah (saas) therefore had a ring made, the whiteness of which is still before my eyes."109

"the inscription engraved on the ring of rasulullah (saas) was 'muhammad rasulullah,' of which in the first line was engraved 'muhammad,' in the second line 'rasul,' and in the third line 'allah'."110