Install Hydroxygen icon theme in Ubuntu 12.10
How to add the Hydroxygen icon theme to your Ubuntu 12.10 system
Here's how you can install the Hydroxygen icon theme in Ubuntu 12.10.
1. Open a terminal window.
2. Type in the following commands then hit Enter after each.
sudo apt-get install hydroxygen-icons
gsettings set org.gnome.desktop.interface icon-theme 'hydroxygen'
For more, see the original article at the link below.