Square-Beam icon theme is redesigned and developed by the same guy who release Square icons for Linux (Eep Setiawan), it is based on Faenza, NITRUX, Moka, and Pacifica icon sets. This icon theme is elegant offers wide variety of icons, which contains more than 30,000 different icons. It can work on any theme whether light or dark. You can use Unity Tweak Tool, Gnome-tweak-tool or Ubuntu-Tweak to change themes/icons.
To install Square Beam icon theme in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal: