The Melbourne Mint began producing Australia's silver florins in 1916. Between 1916 and 1919 the coins that they issued featured an 'M' mint-mark on the reverse below the date. After a hiatus in production in 1920, the 'M' mint-mark was removed in 1921 as the Commonwealth Government wanted dies to be interchangeable between mints in Australia. From this point forward the design of the circulating Australian Florin would remain unchanged until the death of George V in 1936.
The mintage of the 1921 Florin was 1,247,112 which is somewhat low compared to its immediately comparable dates. This slightly lower mintage seems to be responsible for higher values across all grades although the difference is not substantial nor is it always the case. The year is relatively affordable although interested collectors may do better looking at the similar but more affordable 1917-M, 1918-M, or 1925.