Australia florins with Elizabeth's portrait are made out of 0.18 troy ounces of silver. As such, they carry value due to precious metal content. To compute the basic value of one of these coins, find the current price of silver at kitco.com and multiply by 0.18. For instance, at this writing silver is running at $27 US dollars per troy ounce, so a florin contains 0.18 x 27 = $4.86 US dollars of silver. Tomorrow the value will be different, since the price of silver changes every day. Look it up.
The florin in our picture has some discoloration and this means the value will not exceed the basic silver value. If you can find a coin that is fully uncirculated and has no problems like scratches, stains, nicks, or gouges, a collector might pay more than silver value, say $5 more. If the toning you describe is attractive, a similar $5 premium may apply -- but you have to find a collector who likes toned coins, most don't.