I like beautiful graphics, but beauty, as they say, is in the eyes of the beholder, so what I consider beautiful, might not be that to you.

So when I say the icons that come with the Oxygen theme on the K Desktop Environment are not very visually appealing, do not get mad if you do not agree. After all, it is just my opinion.

If you are not running a KDE system, the representative icons of the Oxygen theme that I am referring to, are shown in the image below. They are too sharp to the eyes.
KDE Dolphin Oxygen Theme

That is why I prefer icons from the ROSA theme. They are much smoother and a lot more polished than those from the Oxygen theme. If you agree, and want to install or use them on your machine, this article shows you how.
KDE Dolphin ROSA Icons

ROSA theme, the default on Mandriva Desktop and ROSA Desktop, is based on the Elementary theme designed by Daniel Foré. It is available under the terms of the GNU General Public License 2 (GNU GPL). To download it, click here. Download the file ending in .tar.gz. Save it to your home folder or any folder under it. If you are using Firefox, it should be saved in the Downloads folder by default.

The next step is to extract the folder from the archive. To do that, start Dolphin and navigate to the folder you saved the .tar.gz file into. Right-click on it and select Extract > Extract Archive Here from the context menu.
Extract ROSA Archive

After that simple operation, you should see another file named rosa-1.0.6. Rename it to rosa. (Right-click on it and select Rename…) Your working folder should now show the file as in this image. You may now delete the .tar.bz2 file.
Rename ROSA Theme Folder

Next, you want to copy or move the rosa folder to the /usr/share/icons directory. That is where system theme folders are located. This step is better performed from the command line, so launch a shell terminal. If you are using Kubuntu, Linux Mint KDE or any other distribution that uses sudo, use the sequence of commands shown in the image below to copy the folder. If you are using the Fedora KDE Spin or any other distribution that uses the root user account, you will still have to use the same commands, but must first su to root. The operation should be completed in about 5 seconds.
KDE Copy ROSA Theme Folder /Usr

After the operation has completed, you have to tell the system to use the new theme. To do that, start System Settings, the KDE control center, and click on the Application Appearance button.
KDE System Settings Appearance

On the next window, shown here, click on the Icons tab. If you have not installed any other theme but the ROSA theme, you should see two listed. Oxygen, the default, and ROSA. Select ROSA Theme and click the Apply button. Close System Settings.
KDE Change Oxygen Theme ROSA

When you launch Dolphin, it should be using the new icons. But it will be showing the generic icons for the folders. The final task is to select folder icons that reflect their contents.
KDE Dolphin ROSA Icons

To do that, right click on a folder and select Properties from the context menu.
KDE Dolphin ROSA Folder Icons

Click on the icon for the folder.
KDE Dolphin Folder Icon Properties

On the window that opens, which is shown below, select the appropriate icon for the folder. Repeat this step for the other folder. Note: Not all folders can be customized this way. One or two will still be using the generic one.
KDE Dolphin Icon source