Such pearl oyster shells in crescent form were used as money in parts of Papua New Guinea until the 1960s. The most valuable were the red kina. The color did not occur naturally, but was generated by rubbing the originally yellowish shell with red ochre powder. If the respective owner repeated this process over a period of time, he increased the ruddy color of the shell and therefore its value.
Red kina were always the possession of men, but women wore them as decoration and display of wealth.