Commemorative crowns (full crowns, or five shillings, or two half crowns) were minted in 1935, 1949, and 1953 for the Treaty of Waitangi, a royal visit, and the coronation of Queen Elizabeth II, respectively. All were one-year types.
A total of 458,148 coins of the denomination were minted, of them 201,148 silver and 257,000 cupronickel.
According to Encyclopaedia of New Zealand 1966, the original specifications for the coin were (in measurement units of the time):
Diameter of Coin: 1.525 inches
Standard Weight: 436.36363 grains
Remedy Allowance (margin of error in weight): 2.000 grains