When diamonds come out of the ground, they have a frosty skin on them. This is because diamonds were formed deep in the earth and brought to the surface by volcanic action. Once they are on the surface, they frequently tumble around in rivers or on the ground. All of this activity beats up the diamond quite a bit and leaves a course surface that looks a lot like a frosted window pane.

Many centuries ago, men discovered that when the frosty outer edge was polished off the shiny surface below was much more beautiful. This ushered in the practice of diamond cutting. Over the years, especially the last 170 years

Historical perspective on art of diamond cutting