How to pay Zakah on gold?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the amount of gold has reached the Nisaab (the minimum amount liable Zakaah) that is 20 Mithqal (a measure which is equivalent to 85 grams of pure gold, 1 Mithqal = 4,25 grams) then one should pay half a mithqal as Zakaah; i.e., 2.5% of the value of gold. If the amount of silver has reached 200 Dirhams, which is the equivalent of 595 grams of pure silver, one should pay five Dirhams as Zakaah; i.e., 2.5% of the value of silver. If the currency is equivalent to the value of 85 grams gold, one should pay the Zakaah. One has to pay Zakaah of his money with two conditions: 1- It should complete the Nisaab, itself or by adding it to other earnings. 2- One Islamic year (lunar) should be passed after possessing the money.

Allah knows best.