Breaking the test material is essential. That's what determines the engineering limits of any applications, and also the failure modes for exceeded tolerances.

Breaking the test material is essential. That's what determines the engineering limits of any applications, and also the failure modes for exceeded tolerances. 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. Most of those are potentially destructive. Perhaps this one was more for optical properties? Refractive index, absorption spectra?