She has to pay zakaah on her jewellery in the future each year if it reaches the nisaab (minimum threshold)… as for the years that have passed, before she came to know that zakaah must be paid on jewellery, she does not have to do anything about them, because she was unaware of that and because there is some element of confusion concerning this issue, since some of the scholars do not think that it is obligatory to pay zakaah on jewellery that is worn or is prepared to be worn. But the more correct view is that it is obligatory to pay zakaah on it, if it reaches the nisaab and one full (Hijri) year has passed, because of the evidence of the Qur’aan and Sunnah to that effect.
Thirdly:
Zakaah on jewellery that is prepared to be used applies to jewellery of gold and silver. Based on this, there is no zakaah on gems that you have bought, if they are not gold or silver.
Fourthly:
The zakaah must be paid by the owner of the jewellery, not by the husband.
Shaykh Ibn Baaz (may Allaah have mercy on him) said: “Zakaah must be paid by the owner of the jewellery. If it is paid by her husband or someone else on her behalf and with her permission, there is nothing wrong with that. The zakaah need not be paid from the jewellery itself, rather it is sufficient ti give the equivalent value each time one year passes, according to the value of gold and silver in the market when the year has passed.
Fataawa Islamiyyah, 2/85
But if the gift has been given to you both, and you have not given your share of it to your wife, then you have to pay the zakaah on your share, if it meets the nisaab, which is 85 grams.
The amount that must be paid is one-quarter of one-tenth or 2.5%, so for one hundred grams it is two and a half grams.
And Allaah knows best.
Nisaab
Praise be to Allah.Nisaab ul-Zakat for naqd (gold and silver) is defined as the minimum amount of naqd specified by shari’a below which one is not required to pay zakat, whereas if one’s wealth exceeds it then zakat becomes incumbent.
And it is known that zakat ul-maal (wealth) in shari’a is required for the two types of naqd—gold and silver—and what serves their function in modern times (commonly referred to as cash), whether it is dollars or riyals or pounds or otherwise.
Nisaab for gold as our Prophet (peace be upon him) has informed us (and for currencies made from gold) is 20 mithqaalan, a measure which is equivalent to 85 grams of pure gold (1 mithqaal = 4.25 grams). It becomes incumbent upon anyone who owns such an amount in any form to pay zakat on it in the amount of 2.5%.
Nisaab for silver and currencies made from silver is 200 dirhams, which is equivalent to 595 grams of pure silver (1 dirham = 2.975 grams). Likewise, it becomes incumbent upon anyone who owns such an amount in any form to pay zakat on it in the amount of 2.5%.