I don't like dark colors for windows and applications in my Desktop Environment, but if you're reading this, you don't share my opinion and you also use KDE, you might be interested in a set of icons called: newKDEGray.
The Icon Set is very complete and covers all the places and applications of KDE. It can also be used with another color scheme, for example in my case they look like this:
If you want to install it, the first thing to do is download the compressed file from the following link:
Then they unzip it and copy the folder to /home/your_user/.kde4/share/icons. Remember that depending on the distribution, the name of the folder may vary. .kde4 a .kde.