The color of the eyes should always be as dark as possible, with 1A the best. It is not so much a functionality reason, since the eyes can work either light or dark, but an all important type trait. As the eye color gets lighter it softens the appearance of the gaze, diminishing the fearlessness of Rottweiler expression.
Another factor in striving to keep the eye color dark is it's difficulty maintaining it once light eyes are introduced into the blood line. Interestingly, the German eye chart allows a range of 1A-5B, however, to be more precise one can often observe shades of eye color in between these numbers. Therefore half shades are also possible. Example 1 A 1/2, 2 B 1/2, etc.
Shape and placement of eyes (subcategory):
The shape of the eye should always be almond with tight fitting lids. Round eyes are a fault. Hairless lids are a fault and an indication of a problem. The distance of the eyes from each other and their location on the head is also of importance. The eyes should lie at a 10-15 degree angle above the bridge of the nose (see fig 5). Best set wide apart.
Below is a chart with an approximation of the correct proportionate distance which the eyes should be set apart. This chart is taken from Dr.Carla Lensi's book on the Rottweiler. She marks the angle at which the eyes should sit in it's placement above the bridge of the nose ( approx. 10-15 degrees). The eyes ideally should also be set 1/4 the distance of the width of the top skull from ear to ear. For example if the top skull measures 15 cm across then the eye should sit 3.75 cm from the center of the stop.
Some faults that occur with eye placement:
1. Eyes set too far apart
2. Eyes set too close together
3. Eye shape (lids) of different size
4. Eyes set too low of an angle( below 10 / 15 degrees)