If yes, a set of how many diamonds shall I set up?
Thank you 
You don’t need master stones for the diamond practical exam. However, if you plan on grading diamonds professionally, it’s a good idea. As for how many stones your set should include, that depends on your budget, of course. Here is some advice from Donald Clark’s article on color grading white diamonds:
You don’t need diamonds in every color grade. You only need the ones you’ll actually use. If you don’t expect to grade diamonds below M in color, don’t seek out masters for the lower grades. A starter set might just include grades E to J. You can add more later.
Hope this helps. Good luck!
Pedro
IGS Admin
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