Majority of scholars hold a view that a currency‟s permissibility is not invalidated if its value diminishes. This perspective is founded on the premise that conventional forms of currency are also subject to fluctuations in value. Financial securities like Halal stocks also go through swings in prices due to market and economic factors.
Riba al-Fadl is described as an unlawful excess in the exchange of two counter-values where the excess is measurable through weight or measure. The concept is based on some Ahadith according to which if gold, silver, wheat, barley, dates, and salt are exchanged against themselves, they should be spot and be equal and specified. If these conditions are not found, this transaction will become Riba al-Fadl.
Islamic Economics Project 