Western shirts pearl snaps

[shadowrider]

Hey folks,
kind of a silly question today. I was looking at a couple of western style shirts I have. They feature white pearl snap buttons: one of these buttons cracked and upon close inspection I could see it's made of plastic.
I am wondering if all these type of buttons are plastic nowadays, and if they have always been like that. Or maybe, as I suspect, they were made of mother-of-pearl back in the day?

Any expert on western wear could weigh in?

 

[Bamaboots]

I have a number of western shirts and my Wranglers have plastic snap covers and my RRL, Polo and my older Pendleton's all have MOP.

 

[Americanaaa Mark]

Unless it's metal like I have seen on some iron heart overshirts

 

[shadowrider]

Thanks for the answers.
Any tips on how to tell if the snap covers are palstic or actual mother of pearl, especially if buying online?
I think it's be a bit more tricky than regular buttons, where the rough back is usually a giveaway.