"The sample looked like an ordinary piece of glass, 4 inches square and transparent on both sides. It’d been packed like the precious specimen its inventor, Adam Khan, believed it to be—placed on wax paper, nestled in a tray lined with silicon gel, enclosed in a plastic case, surrounded by air bags, sealed in a cardboard box—and then sent for testing to a laboratory in San Diego"
We actually broke low quality diamonds with a hammer. They are also very easy to burn.
What is very hard is scratching diamond. If you combine the properties of different materials like diamond on the surface, and something that absorbs impacts inside it could be a wonderful material.
Breaking it, of course, would be something that any device designer would do in the course of characterizing or evaluating it as a component for a new product.
Whether that would have been done on the first sample is something that's strictly between the AKhan and the evaluator.
It's all fine and good if your device can survive a drop from 1m onto a hard floor without cracking or chipping, but if a fall from 2m then results in a cloud of razor-sharp glass flechettes, that shred all flesh in a 5m radius, you're probably not going to want that particular screen treatment in a consumer product.
But this test material was not supposed to be used for that, I guess. I'm not sure how they were supposed to evaluate it.
Personally, I'd want to do all of the following:
Put it in a rock tumbler with a bunch of keys and coins.
Scratch it with a steel razor blade.
Drive a galvanized deck nail through it with a claw hammer.
Drill a hole through it with a SiC drill bit.
Heat it up with a propane torch.
Put it in a freezer.
Drop it from 2m onto a hard floor.
Bend it in multiple directions.
Pinch it until it cracks.
Try to find a resonance frequency with ultrasound.
Perhaps this one was more for optical properties? Refractive index, absorption spectra?
An initial evaluation would be measuring things like how much light energy of what frequencies is able to penetrate the coating. Is the viewing angle acceptable for a consumer device, etc.
Hitting it with a hammer can always come later when they determine that it is a good display glass first.
Breaking it into a number of a pieces with a laser is beyond the scope of testing its ability to resist scratches.