Abu Dawud Book 29, Hadith Number 4226.
Chapter : Wearing gold by women.
Narated By Asma’, daughter of Yazid : The Prophet (PBUH) said: Any woman who wears a gold necklace will have a similar one of fire put on her neck on the Day of Resurrection, and any woman who puts a gold earring in her ear will have a similar one of fire put in her ear on the Day of Resurrection.