Urwah (may Allah have mercy on him) narrates from Sayyidah Aishah (may Allah be pleased with her) that she used to adorn her nephews with gold.
If the narrator remembered it correctly, this was at a time when they had not reached puberty. Imam al-Shafi'i (may Allah have mercy on him) says that children may be dressed in what men and women may wear, and they may also wear jewelry on the day of Eid. But Imam Malik bin Anas (may Allah have mercy on him) disliked it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة العيدين / 6246