Hi Jimmy!
I have used the pencils, but not the pastel sticks themselves. One of the nice things about the Faber-Castell products is that they do test their colors individually for light-fastness and provide a chart of the results with the product. Not surprisingly, some colors are more light-fast than others.
If you are particularly concerned with certain colors, you might benefit from finding a set in a store and seeing if you can get a look at the chart inside the box. I took a look on their website and did not find it posted there, but you might be able to ask to have a chart sent to you. Here's the
site.
I love working with the pencils! The sharpen nicely, and don't break off as many pastel pencils do. They have a terrific range of colors that match perfectly across their product lines.
Good luck!