Well that's cool, Christopher. You have an old florin from the Fiji Islands. The one in our picture is the first issued, in 1934. After that, the shield design on the back stayed the same, but the monarch on the front changed as they did in England: from George V to George VI to Elizabeth II.
Composition is important to these coin. Some are silver, and some are copper-nickel, as follows:
1934 to 1941: 0.182 troy ounces silver
1942 and 1943: 0.327 ounces silver
1945: 0.182 ounces silver
1946 to 1965: copper-nickel
Copper-nickel pieces carry low value:
COPPER NICKEL FLORIN
circulated: $1 US dollar approximate catalog value
fully uncirculated: $7
If you have a silver coin, first compute its base silver value by multiplying the 'spot' price of silver by the 0.182 or 0.327 fraction. At today's spot price around $19.20 US dollars per troy ounce, the base silver value of a 1945 coin would be 0.182 x 34.50 = $3.50. Tomorrow the price of silver will be different. Look it up on web sites like kitco.com.
In addition to the base silver value, some of the older coins carry addition premiums due to collector demand. This really kicks in for nice-looking, problem-free, uncirculated specimens. Here are some typical additions:
1934 to 1941: add $10 for well preserved coins, add $100 for fully uncirculated coins
1942 and 1943: add $3 for well preserved coins, add $8 for fully uncirculated coins
1945: add $30 for well preserved coins, add $220 for fully uncirculated coins
All these added values are approximate. To qualify for high-end additions, the coin must be very striking to the eye and carry no problems such as scratches, stains, spots, or cleanings.
The later copper-nickel florins are worth basically face value. A collector may pay a few US dollars to add a nice-looking specimen to his or her collection.