Install Pacifica theme on Elementary OS 0.2 (Luna)

$ sudo apt-add-repository ppa:elementary-br/projects
$ sudo apt-get update
$ sudo apt-get install pacifica-icon-theme

Now set the theme using the gsettings configuration tool:

$ gsettings set org.gnome.desktop.interface icon-theme "Pacifica"

If you've already installed Elementary Tweaks, the command above is not required. You can just select the Icon Theme and set it.