Book 27, Question 84
How do gem cutters turn rough stones into gems?
A gem cutter, or lapidary, studies a rough stone to find the best shape.
The stone is sawed, ground, and polished using grit made of very hard materials such as diamond dust. Flat faces called facets are cut at exact angles so light bounces inside and flashes out. Some stones are polished smooth into domes called cabochons. Cutters work with water and masks to stay safe.