8.3 to 4.2 grams. Redemption of old silver coins for new gold coins at par began on October 1, 1897 and lasted until closure on July 31, 1898. During the Taishō era the production of five yen coins was impacted by World War I as a gold embargo was imposed in 1917 by the United States. Even though this embargo was later lifted in June 1919, the Japanese government continued it by importing gold heavily to re-enforce the gold reserve of the Bank of Japan. Government officials at the time had the opinion that no inflation could take place so long as the percentage of gold cover had not been lowered. This embargo was not absolute however, as it was recorded that some gold coins were paid out between 1920 and 1928 in very small amounts. The gold embargo was later lifted in January 1930, only for it to be re-imposed on December 31, 1931. Five yen coins were last minted in gold during this brief time to act as a reserve for gold certificates. None of these coins were in general use afterwards as the medium of commerce consisted of nonconvertible 5 yen banknotes. Modern five yen (1948-) Almost 20 years would pass before the Japanese government authorized the production of a new five yen coin. These new coins were first struck in 1948 and are made of a brass alloy consisting of 60 to 70% copper, and 30 to 40% zinc. Using this type of alloy combination is now a remnant from when World War II era weapons were scrapped to produce the coins. These coins feature a pigeon within a circle on one side and the National Diet on the other and were only minted for two years. Two different varieties were made in 1949 which included the old pigeon type coins, and new coins featuring a hole in the center. These first holed five yen coins use an old style Japanese script known as Kaisho. The Japanese government added the hole in the center of the coin to save material costs. The overall design of the coin featuring rice, water and a gear on the obverse, and tree sprouts on the reverse has not changed since this time. The final design which is minted today uses a modern style script which was first added in 1959. Five yen coins made headlines in 1999 in regards to