The dead giveaway for a pastel of any quality is the brownout line. They all have it. It is the line on the side where the yellow of a hatchling or the brown of an adult fades into the belly.
I'll show you a few examples.
This is my pastel male. You can see quite clearly the brown line that runs his length.
http://www.ball-pythons.net/forums/s...ot-...-Pastels
This is a fantastic guide to identifying morphs, and in each of these photos you can see the brown out line. You have to look closely sometimes, but it is there. A clear line running down the length of the animal on it's sides.
The snakes pictured above have it as well.
All pastels have it, high yellow or high brown. This is for me the single best identifier of pastels.
Gale