How can financial securities be considered equivalent to gold and silver, given the resultant problems related to usury in sales and daily financial transactions such as purchasing jewelry and currency exchange, and to what extent does this affect the obligation of Zakat?

The majority of contemporary scholars and Islamic Fiqh academies have assimilated banknotes to the two precious metals (gold and silver) in terms of legal rulings. Thus, Zakat is obligatory on them, and riba an-nasa' (interest due to delay) is absolutely forbidden, as is riba al-fadl (interest due to excess) when exchanging the same currency. Buying gold and silver on credit is Islamically forbidden, and immediate exchange (hand-to-hand) is required when purchasing them with banknotes. Exchanging different currencies with a differential is permissible, because each currency is a distinct category. Transferring money from one country to another is permissible, as the exchange is implicitly realized, and because it falls under matters of necessity.