This quest is triggered once level??? is reached (suggest that it is on completion of Discover the Isle!) and has a 2 day deadline.
This is noted as being a Fixed Date Quest here, for iOS in Month 2012, thus it may have been re-released for Android in August 2013.
- Find 15 Rubies in mermaid searches (Both ruby spins or coins spins works)
Credits: Poohbear and Claddagh on Forum