I am going to go out on a limb and guess that it could be both? Some diamonds can come loose from the substrate, but wouldn’t that just focus the applied pressure more on the diamonds remaining(less nails in the bed)?
And wouldn’t one errant larger diamond receive a point force of impact not shared by its buddies? This to my logic would make it very susceptible to “cleavage”.
This article below (originally posted by Cbwx) has very good information regarding commercial-grade diamonds. It even discusses a test where the diamond is placed in a capsule with a single ball bearing and shaken to see how many diamond particles get flaked off.
http://industrialdiamonddirect.blogspot.com/2006/02/industrial-diamond-properties-and.html
Also mentioned in the article is a process called “graphitized”. I’m very curious if that may not be in fact what we witness with the bronze cutter machine in the video above?
Aloha,
Cliff