Sway Black-Base PURPLE is a dark GTK3 theme with purple elements, designed for Ubuntu 12.04 (Precise Pangolin) and for the GNOME 3.4 desktop environment. It is a combination of Originalseed's DarkCold 4 and Swar-Black-Base-Orange.
Sway Black-Base PURPLE was tested only with Ubuntu 12.04 but it should also work with other GNOME based operating systems.
How to install?
For detailed installation instructions please see the following tutorial created by Softpedia: http://news.softpedia.com/news/How-to-Install-GNOME-Themes-in-Ubuntu-11-10-231213.shtml