Good question. The wood when I drill it comes out a deep red/purple but on the outside, especially when coarse sanding or filing turns brown. It is very oily, and when I sand it quickly and with higher grits darkens up. Using something like a belt sander causes very dark marks and could not be used. I think after I get into finer grits (still using 100 on the shaping) the grain will really come out. Googling 'purple heart turns brown', sounds pretty common. I'm going to leave it in the sun for a few days and see :-).
My uncle is a pretty serious wood worker and purchased the wood rough cut in Costa Rica or Panama (can't remember which). If he says its purple heart, I'm going to go with it. In either case, it makes for beautiful scales. Here is a picture as of 1AM. As you can see with the coarse sanding the wood becomes completely brown but I can assure you it is purple on the inside :-).
https://goo.gl/photos/Ryk6aHLHwGpLXTwS9
Worth noting the wood is substantially harder than anything I have ever seen or worked with. Even with a steel file, it takes work to shape. Really quite awesome and fun to work with. I'm going to do another night of sanding and profiling and then coat it with tung oil, then wax.