ink. Exceptions occurred with: 2 colones provisional issue: black 5 colones provisional issue: orange 10 colones provisional issue: blue 500 colones series B: black 1,000 colones series A issue: dark blue Every issue also features the signatures, date, and the agreement number printed in black. Banknote reform In 2011 and 2012, Costa Rican banknotes underwent a reform and were replaced by a new series, with each banknote a different color and size. Two new denominations were introduced as part of the reform; 20,000 and 50,000 colones. The old notes are redeemable at the Central Bank of Costa Rica, but have been replaced with the newer models. In 2020 and 2021, a new series of banknotes was issued in polymer, conserving the same themes of the 2011 series but with slightly redesigned motifs, with the old notes withdrawn in 2022. A redesigned 50000-colón note was not included in the new series, but existing issues remain legal tender. Exchange rate The colón has had an unusual relationship with the U.S. dollar that may best be described as a "crawling peg"; instead of being defined by a constant value to the dollar, the colón instead would grow progressively weaker at a fixed rate of about 3.294 colones per dollar per month. On October 16, 2006, however, this crawling peg was modified due to weakness in the U.S. dollar and the perception that the colón is now undervalued. Since October 17, 2006, the colón is no longer bound to controlled devaluations (known in Costa Rica as minidevaluaciones) by the Central Bank of Costa Rica. With the new system, sistema cambiario de bandas, the exchange rates posted by the Central Bank are a "reference" and each authorized financial institution can determine their value independently in hopes that the free market will provide a mechanism to keep them reasonable. The exchange rate is now free to float within a currency band referenced to the United States dollar. The floor of the band has been set at a fixed value, while the ceiling changes at a fixed rate. In practice the exchange rate has remained fixed at the lower value of the currency band. Nicknames The colón is sometimes referred to as the peso, which was the name of the Costa Rican currency before the colón, until 1896. This is very common across Hispanic American countries, where most have (or had at some point) currencies called pesos.