Until 1987, Fiji fifty cent coins were the same size and shape as their Australian counterparts.
In 1990, Fiji switched to coins of the same size as the earlier (large) dodecagonal coins but made of steel instead of copper-nickel.
In 2009, Fiji switched to a new type of fifty cent coins. These are smaller in size than the earlier ones and have a round shape. The 2009 issue retained the old design and the Queen's effigy (even though Fiji was already a republic at the time).
After Fiji was fully suspended from the Commonwealth of Nations in September 2009, new coins featuring native animals in place of the Queen were minted by the Royal Canadian Mint in Winnipeg in 2012, becoming available in 2013.
According to Krause:
From 1975 to 1987, fifty cent coins were copper-nickel, 12-sided, and measured 31.55 mm with a mass of 15.55 g.
From 1990 to 2000, fifty cent coins were nickel-plated steel, 12-sided, and measured 31.55 mm with a mass of 13.44 g.
2009 and later issues are nickel-plated steel, with round shape (with a 12-sided pattern of the rim to remind of the earlier issues), and measure 26.5 mm with a mass of 6.5 g. | 
