Question: If one has gold or silver jewellery, however it is composed of a mixture of another metal that is neither gold or silver. Is Zakaah to be paid upon it?
Answer: Regarding the likes of this issue, it is said: Consideration is given to what it mostly consists of. If the major constituent of the jewellery is one of the two precious metals (gold and silver), then Zakaah is paid upon it. And if the major constituent part is other then these, then there is no Zakaah [upon that piece of jewellery] – except the general Zakaah that was indicated in the previous question.
Source: “Al-Masaa’il Al-`Ilmiyyah wal-Fataawa Ash-Shar`iyyah – Fatawash-Shaikh Al-`Allaamah Muhammad Naasir Ad-Deen Al-Albaanee Fil-Madeenah Wal-Imaaraat.” (# 50, p. 120)
Listen here to brief series of lectures on the topic of Zakaah based upon the rulings of the Major Scholars of Sunnah.