Rubees are gems that are needed to be collected in Splash Rescues Friday RX in order to pass each level. Once collected, they are used to create a portal. The colour of rubees changes depending on which location they are from. While gems of a similar nature did exist in the original Ninja Splash Rescues Friday, they were not given the name "rubee" until SRX, and the original gems used the stock gem sprite from Yoyo Games.