Fade External References

To help identify which parts of a drawing are external references you can adjust the Fade control to make these stand out against your design work. To access these controls go to the Insert TAB on the Ribbon > click on the Reference panel name to expand the options.

This value is always preset, by default AutoCAD 2011 introduced a fading of 70%, AutoCAD 2013 introduces a default fading of 50%.