When you say "artificial" stag, do you mean plastic? Or do you mean real Sambar stag vs. red stag or elk or jigged bone? If you're referring to stag vs. plastic or polymer, it's pretty easy. Just remove the grips and look at the back. Stag, elk, and bone will tend to be a little rougher on the back and you will be able to see the grain or texture of the natural material. Plastic or polymer will be smooth and you won't see any grain.
Being able to tell Sambar stag from other types of stag or elk is usually a little more difficult. I have both and while some individuals who are much more discerning than I am can tell the difference, I have a real tough time.
I have at least two pairs of Ajax stag grips and, if I remember correctly, Ajax used real stag when they were in business. I don't think you have anything to worry about.