How Diamonds Work
To cut a rough diamond down to a manageable size, the cutter must cleave it along the diamond's tetrahedral plane, where it is the weakest. A wax or cement mold holds the diamond in place while the cutter carves a sharp groove along the plane. The cutter places a steel blade in the groove and forcefully strikes it, cutting the rough diamond in two.
Original Article Source Credits: How Stuff Works , https://science.howstuffworks.com/
Article Written By: Kevin Bonsor
Original Article Posted on: NA
Link to Original Article: https://science.howstuffworks.com/environmental/earth/geology/diamond3.htm