How is the value of the zakat nisab for worn gold that has been owned for a full year calculated, given the differing gold prices depending on the importing country, and is the purchase price or the selling price considered in the calculation?

Scholars differed regarding the zakat on jewelry, and the opinion that it is obligatory is more cautious and absolves one's responsibility. If the gold reaches 85 grams and a year passes over it, zakat becomes obligatory on it, which is a quarter of a tenth (2.5%) of the gold itself, or of its monetary value at market price in the zakat payer's country. For different karats, a quarter of a tenth of the value of each type is to be given.