Desert Fever: Being a most baneful affliction, unresponsive even to the letting of blood, its course reversible only by the light of a Damcyan sand pearl.
- —Final Fantasy IV
Sand Pearl (砂漠の光, Sabaku no Hikari?, lit. Desert Light), also known as the Sand Ruby, is a recurring key item in the series. Whenever it appears, the Sand Pearl acts as a cure to the illness known as the Desert Fever.
When Cecil Harvey and Kain Highwind don't return from their mission, Rosa Joanna Farrell goes on a journey to find them. In the Kaipo desert, Rosa is stricken with Desert Fever and taken to the town where she is looked after. When Cecil, Rydia, and Edward Chris von Muir visits one of the houses they meet Rosa and are tasked with finding the Sand Pearl in order to cure her from the illness. With the help of Edward and Rydia, Cecil obtains the pearl from the Antlion's Den by defeating the Antlion and takes it back to Kaipo. On the next day, Rosa decides to join Cecil.