Anas bin Maalik Radiyallahu 'Anhu says that the ring of Rasulullah Sallallahu 'Alayhi Wasallam was ,made of silver and the gem stone was from Abyssinia (JA)
English reference (JA): Book 11, Hadith 82 (JA)
Arabic reference (JA): Book 12, Hadith 87 (JA)