[Source] Czech crystal round cabachons

I am new to jewelry making and I am really stuck on this… I have
spend hours on the internet and have looked in the Thomas Register
already. I am looking for a wholesale supplier for these:

Clear zech glass cabochon round crystals in different sizes from 12
mm - 25

Also I would like any advice on how people find really specific,
unique jewelry components. I have abandoned projects before because
I can’t find the right piece.

Thank you!