Does zakat become obligatory on ornamental gold that exceeds the nisab threshold if years have passed without it being worn, knowing that it is bought and sold from, and how is the zakat for the past years to be paid in this case?

The majority of scholars, including the three schools of thought (Madhahib), are of the opinion that gold prepared for permissible use is not subject to zakat (definition). It is not necessary to use the jewelry to avoid zakat according to the majority; rather, as long as it is prepared for use, zakat is not obligatory, even if it is not used during the year. It does not matter if some of it is sold or exchanged for something else, as long as the intention for its use does not change. As for the view of Abu Hanifa and some contemporary scholars, it is that zakat is obligatory on jewelry even if it is prepared for use. The first opinion is the one adopted for fatwa (definition), although the second opinion is more cautious. If the wife wishes to be cautious, she should pay zakat for all past years. If she is unable to determine what she owned, she should make an earnest effort and pay what will give her certainty or a strong presumption of clearing her liability.