South African rand due to relatively high-quality counterfeit notes in circulation. In 2011, the South African Reserve Bank issued 100-Rand banknotes which were defective because they lacked fluorescent printing visible under UV light. In June, printing of this denomination was moved from the South African Bank Note Company to Crane Currency's Swedish division (Tumba Bruk), which reportedly produced 80 million 100-Rand notes. The South African Reserve Bank shredded 3.6 million 100-Rand banknotes printed by Crane Currency because they had the same serial numbers as a batch printed by the South African Bank Note Company. In addition, the notes printed in Sweden were not
Optimum currency area rationale behind the creation of the euro is that the individual countries of Europe do not each form an optimal currency area, but that Europe as a whole does. The creation of the euro is often cited because it provides the most modern and largest-scale case study of an attempt to identify an optimum currency area, and provides a comparative before-and-after model by which to test the principles of the theory. In theory, an optimal currency area could also be smaller than a country. Some economists have argued that the United States, for example, has some regions that do not