The main reason why the Tango desktop project was initiated was to ensure that the applications don’t appear alien when they are run in different desktop environments. Enough care is taken that it doesn’t come down to the merging of unique styles of different desktop systems. Furthermore, the people behind the project strive to ensure that the appearance doesn’t seem drastically different on different platforms.

A common color palette is used for delivery of consistent look to all the icons. Please note that visual styling gets heavily influenced by the choice of colors. When drawing icons, the common practice is to utilize the palette in the form of a base, and applying it on to the larger areas. Creation of highlights and shadows through changing values, shading with gradients and making minor saturation changes are also permitted. It’s not necessary to include colors from this set alone, and the developers are free to use additional colors of their choices.

Additionally, there are certain icon attributes that define those icons to be a part of the Tango project. Let’s go over some of those visual aspects as follows:

Highlights – The objects’ edges reflect light a little more depending on the position of the observer. When talking about the highlights, the Tango project team inherits the same style as Thunderbird/Firefox Winstripe/Pinstripe designed by Stephen Horlander and Kevin Gerich, which moves away from the reality by creation of a very subtle second inner outline of the objects.

Glossy reflections – It is used in objects having a reflective surface in the real world, for instance metal, glass, plastic etc.

Object outline – Every Tango project icon is stroked with a thin outline so as to improve its contrast. The stroke size is normally 1 px at lower resolutions, and doesn’t scale along with the icon.

There are many more icon theme guidelines that are pretty extensive, and hence out of scope of this article.