How is the value of the euro calculated for Zakat purposes: is it according to the official exchange rate, the black market rate, or the exchange rate at the time of conversion? And is Zakat obligatory on pieces of gold purchased for manufacturing but not yet manufactured, and if so, how is their value estimated and included with other funds when calculating Zakat?

Different currencies must be combined to complete the nisab (definition). Zakat (definition) al-mal (money zakat) is paid in the currency the muzakki (person paying zakat) possesses, and it is permissible to pay its equivalent value at the time of payment, prioritizing what is most beneficial for the poor, and based on what it can be sold for. Gold prepared for making jewelry is subject to zakat if it reaches the nisab, and it is combined with money. However, if it is manufactured and becomes used jewelry, there is no zakat on it according to the majority of scholars.