Sayyidah Umm Salamah (may Allah be pleased with her) said: I used to wear a gold necklace, and I said: "O Messenger of Allah (peace and blessings be upon him), is this kanz (hoarded treasure)?" He (peace and blessings be upon him) said: "Whatever reaches the amount on which zakah is to be paid, and its zakah is paid, is not kanz."
Only Thabit bin Ajlan narrated this, and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7550