The Book of Adornment
48/47. Chapter:
Description of the Ring of the Prophet [SAW]
Sunan an-Nasai
أَخْبَرَنَا أَحْمَدُ بْنُ سُلَيْمَانَ، قَالَ حَدَّثَنَا مُوسَى بْنُ دَاوُدَ، قَالَ حَدَّثَنَا زُهَيْرُ بْنُ مُعَاوِيَةَ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ، قَالَ كَانَ خَاتَمُ النَّبِيِّ صلى الله عليه وسلم مِنْ فِضَّةٍ فَصُّهُ مِنْهُ .
It was narrated that Anas said: "The ring of the Prophet [SAW] was made of silver and its stone (Fass) was made of silver too."
Reference : Sunan an-Nasa'i 5200In-book reference : Book 48, Hadith 161English translation : Vol. 6, Book 48, Hadith 5203