Umar bin Ya'la al-Ta'ifi al-Thaqafi narrates from his father, and he from his grandfather (may Allah be pleased with him), who said: I came to the Prophet (peace and blessings be upon him) while there was a gold ring on my finger. He (peace and blessings be upon him) said: "Have you paid its zakah?" He said: I said: Is there zakah even on this? He (peace and blessings be upon him) said: "It is a huge ember." Al-Walid said: I said to Sufyan (may Allah have mercy on him): How is the zakah of a ring to be paid, when its amount is only a mithqal or about that? He said: It is to be added, by weight, to the things on which zakah is obligatory, and then its zakah is paid.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7585
Umar bin Ya'la al-Thaqafi narrates from his father, and he from his grandfather (may Allah be pleased with him), that a man came to him (peace and blessings be upon him) wearing a large gold ring. The Prophet (peace and blessings be upon him) said: "Have you purified it (by paying its zakah)?" He said: O Messenger of Allah, what is its zakah? He said: When the man turned away, he (peace and blessings be upon him) said: "It is a huge ember."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7586