Honestly I don't know. I wish I could go to chinchilla shows that have a lot of different colors and see them in person. I'm in kind of a secluded situation myself living where it's a bit warm for large scale operations.
My first thought on this one is the fur is extremely short. The fur closest to the skin is dark and then the tips are light on the belly. So I'm guessing it's just the tips are very shallow because of the shortness of the fur so its legs are pulled forward exposing those deeper colors. I would expect in a normal stance it would not be near as noticeable. Although the forelimb colors on my own standard vary quite a bit.
So if you can go to chinchilla shows that would be ideal. If I remember right sapphire and RPA are recessive so both sire and dam must be Sc and RPAc.
If you hang around here for any length of time you'll be mentoring people and learning about all kind of crazy things that can go wrong with pet owners and chinchillas. The forums are active and it comes and goes in waves. I strongly recommend Empress Chinchilla and MBCA for more information. They are good communities and resources for breeders.
http://www.mutationchinchillas.com/index.htmlhttp://empresschinchilla.org/‘A‘ole pilikia (Your'e welcome (If I googled that right!))