There are many evidence that refer to the obligation to pay zakat on gold. Among them, in the Al-Quran there is a verse referring to the obligation to pay zakat on gold, which is as follows:

“And (remember) those who hoard gold and silver and do not spend it in the way of God, then inform them of (the punishment of) an indescribable torment. (That is) on the day that gold, silver (and property) will be burned in hell, then their foreheads, and their ribs, and their backs will be lashed with it (while saying to them): This is what you have kept for yourselves, by that is the taste (punishment of) what you kept.” (Surah At-Taubah; Verses 34-35)

Meanwhile, the Prophet SAW said, narrated by Abu Hurairah RA, which means:
“Whoever is the owner of gold and silver and does not pay his zakat, on the Day of Resurrection will be prepared for him a bed of fire heated by hell. With that fire his ribs and back will be burned.” (Sahih Muslim)

With these dalil, it is clear that zakat on gold must be paid on the gold we own.

However, exception is given on the amount of gold savings that is not enough nisab, which is as much as 85 grams. This can be seen from the words of the Prophet SAW which means:
“It is not obligatory on you anything that is on gold until there is 20 dinars (85 grams) and there has been enough obligatory haul on it half a dinar. Anything more than that, according to the same count.”(Hadith narrated by Abu Daud)

Similarly, the original law for gold jewellery is that it is not subject to zakat. This is determined based on the hadith of the Prophet SAW (which means):
“There is no zakat on jewellery.” (Hadith narrated by Ibn Jauzi in al-Tahqiq)

There is also a hadith narrated by Imam Malik in Al-Muwatta’ (which means): 
“Aishah RA used to dress some of her nieces who were orphans in gold ornaments, then she did not pay the gold zakat on them.”

Meanwhile, the former chairman of the International Union of Muslim Scholars, the late Dr. Yusuf al-Qaradhawi has said in Fatawa al-Mu’asirah: “It is well known that the jurists disagree about the obligation of zakat on women’s jewelry if it consists of gold and silver.”

However, the general opinion from the scholars and fatwa councils states that if the gold that is owned is excessive, it should be paid zakat on if it exceeds the limit of uruf that has been set in each state. This is stated in the hadith as follows (which means):

“From Amru ibn Shu’aib from his father from his grandfather, he said: “A woman met the Messenger of Allah with her daughter. On her child’s hand were two thick gold bracelets.” Then the Messenger of God SAW said to her: “Do you pay zakat on this jewellery?” The woman replied: “No.” So the Prophet said: “Do you want Allah SWT to put on you two forms of fire bracelets on the Day of Resurrection?”

Therefore, it can be seen here that indeed the gold of jewellery that exceeds the uruf needs to be paid zakat on.