hawkfive,
Chances or good that what you are seeing is calcium buildup on the stone. Natural stone does not generally loose it's color.
Try a lite mix of water and pool acid in a small area to see if that takes care of the problem.

That probably is a result of salt erosion on the stone. It can happen if the water balance gets out of whack. It may be permanent damage or calcium build-up, which is a common problem with salt pools.

Try thr product below it will last a couple of year before you need to reapply. I use it on my flagstone on my own pool. The high gloss will really make the flagstone stand out. They also make a natural if you prefer.

Here is a link that might be useful: Sealer