Can gold be added to silver to complete the nisaab?
Question

                A woman owns some gold but it does not reach the nisaab (minimum threshold at which zakaah becomes obligatory). She also owns some silver but it does not reach the nisaab. Does she have to pay zakaah on her jewellery if the gold and silver are added together? Please note that this jewellery is for adornment only.
Praise be to Allah.
    Firstly: 

    Zakaah is due on jewellery according to the correct scholarly 
    opinion. This has been discussed previously in the answers to questions no.
    19901 and
    59866. For information on the 
    nisaab for both of them, please see the answer to question number
    64. 

    Secondly: 

    If a person owns both gold and silver, and neither of them 
    reaches the nisaab, but when added together they do reach the nisaab, he 
    does not have to pay any zakaah. Similarly, if a person has 70 g of gold and 
    400 g of silver, he does not have to pay zakaah on them until one of them 
    reaches the nisaab, because of the hadeeth of Abu Sa‘eed (may Allah be 
    pleased with him): “There is no zakaah due on less than five wasqs …” 
    Narrated by al-Bukhaari, 1405; Muslim, 979. And because gold is not the same 
    type as silver, so they cannot be added together, just as other types of 
    things cannot be added to one another to complete the nisaab. Camels cannot 
    be added to cattle, cattle cannot be added to sheep, wheat cannot be added 
    to barley and dates cannot be added to raisins. 

    An-Nawawi (may Allah have mercy on him) said: Gold cannot be 
    added to silver or vice versa to complete the nisaab. There is no difference 
    of scholarly opinion – in our madhhab – just as dates cannot be added to 
    raisins.

    End quote from al-Majmoo‘, 5/504. 

    He also said: The nisaab for dirhams (silver coins) cannot be 
    completed by adding gold or vice versa, even if one owns two hundred less 
    one dirham, and twenty mithqaals less half a mithqaal and so on. There is no 
    zakaah on either of them. This is the opinion of the majority of scholars 
    and it was narrated by Ibn al-Mundhir from Ibn Abi Layla, al-Hasan ibn 
    Saalih, Shareek, Ahmad, Abu Thawr and Abu ‘Ubayd. Ibn al-Mundhir said: And 
    al-Hasan, Qataadah, al-Awzaa ‘i, ath-Thawri, Maalik, Abu Haneefah and all of 
    ashaab ar-ra’y said that one of them may be added to the other.

    End quote from al-Majmoo‘, 5/504 

    Ibn Qudaamah (may Allah have mercy on him) said in 
    al-Kaafi: Gold cannot be added to silver to complete the nisaab because 
    they are two different types. … And it was narrated from Ahmad (may Allah be 
    pleased with him) that he added them together because they are used for the 
    same purpose and in the same way. End quote. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The 
    correct opinion is the first one, that gold cannot be added to silver to 
    complete the nisaab except when they are used for exchange. That is because 
    wealth used in exchange is prepared for the purpose of trade, so (in this 
    case) the gold and silver are trade goods.

    From Sharh al-Kaafi. 

    He also said: Even though they are used for the same purpose 
    and in the same way, that does not mean that they can be added together to 
    complete the nisaab, because the Lawgiver has prescribed a specific nisaab 
    for each of them, which implies that zakaah is not due on anything less than 
    that, and there is no report from the Prophet (blessings and peace of Allah 
    be upon him) that he added one of them to the other. Just as wheat cannot be 
    added to barley to complete the nisaab, even though they are used for the 
    same purpose and in the same way, the same applies to gold and silver.

    End quote from Majmoo‘ al-Fataawa, 18/248. 

    And Allah knows best.