The Gilbert Islands in the southwest Pacific Ocean, all 30 of them, became the Republic of Kiribati in 1979. Since then the Kiribati government has issued many fine looking coins for circulation and collectors. Since they are all modern coins, they are worth face value unless they are made of gold or silver, in which case they are worth bullion value.
The 1, 2, 5, 10, 20, and 50 cent coins are made of non-precious metal (bronze, copper, nickel, brass), as are some 1, 2, and 5 dollar coins.
The 1979 5 dollar coin is made of silver, containing 0.4527 troy ounces for the regular coin and 0.8375 ounces for the proof coin. (Proof coins are special coins made for collectors.) Other $5 coins are made of copper-nickel.
Higher denomination coins, such as the $10, $20, and $150 denominations, are made of silver and gold.
To find the value of a precious metal coin, multiply its metal content in troy ounces by the current value of gold or silver, as found on web sites such as kitco.com.
Another Kiribati coin, made of the precious metal platinum, is described at this CoinQuest link.