The article is a prank. You won't make a diamond without a sealed chamber filled with a well crafted atmosphere. (Just a question, but does the end-result look anything like a diamond to you?)
Also, if you want to try any "dry" recipe in a microwave, put a glass with some water near it. Otherwise you risk damaging something.
If I'm not mistaken a Youtube channel called "Night Hawk in Light" made a series of videos some years ago about creating various types of gems using a microwave, like rubis and diamonds. Amazing channel overall.
