What colour are his eyes? Does he have molted (spots) on his skin around his eyes, muzzle, and genitals? I'm thinking either pearl or champagne. Do you have any knowledge on what colour his parents were?
The lighting in both pictures makes it really hard to judge - ideally, the light should be overcast, about 2pm in the afternoon on a slightly cloudy day is the absolute best. If you can't swing that, outside in natural light with the sun behind the photographer rather than behind the horse is always going to be next best.