Some of the coinage on Rime Isle consists of Rime Isle Silver, and Rime Isle Doubloons.
Fafhrd and the Gray Mouser pay for their docking fees at Rime Isle with Sarheenmar Doubloons, Lankhmar Rilks, and Rime Isle Gold in the story Rime Isle.
In The Curse of the Smalls and the Stars, we learn that Eastern Half-Pennies and Iron Tiks are very small coins. Also, a wager is made on a backgammon game of one Gold Rilk to two Silver Smerduks. This may give some basis to determine the relative worth of the mentioned coins.