I think "sharpest" may be a bit of an exaggeration in the title. While the technique is cool and I recommend watching more of this guy's videos, it's by no means the sharpest knife. I have a small business hand sharpening knifes using a similar technique (Japanese ceramic whetstones and hones) and I can easily make one much sharper within a few minutes. It's a great hobby and a good way to make some side cash if you learn your stuff.
You have a business where you regularly seperate beach sand into its components and make a knife out of it and sharpen them?
The claim here is not that this is the sharpest knife ever and it just happens to be created in a home lab using sand and a microwave. The claim is that among all knifes made from sand, using a microwave, this one is the sharpest - and I am not convinced that you have such a knife, let alone one that is also sharper.
Yeah, I don't understand why anyone would nuke beach sand when coffee can carbon foam furnaces are trivial to make.
And in about 2 seconds, I can get a really damn sharp "knife" by dropping a wine glass on the floor to induce conchoidal chipping. My foot and hand can attest to them being as sharp or sharper than any surgical instrument or Japanese-angle ground knife.
