Signet-rings - Section 1 Mishkat al-Masabih 4387
Arabic hadith text
وَعَنْهُ أَنَّ نَبِيَّ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ خَاتَمُهُ مِنْ فِضَّةٍ وَكَانَ فَصُّهُ مِنْهُ. رَوَاهُ البُخَارِيّ
Translation
He said the Prophet’s signet-ring was of silver as was also its stone. Bukhari transmitted it.