If you are looking for anything that you'd be able to sell as "diamonds" similar to a jewelry store, no, you can't.
Nothing
The human will be cooked from the inside out.
It shrinks
it might explode
The lamp will explode.
if you put the whole tube in there it will explode
Microwave oven.
microwave mirror lightbulb fireplace
The microwave oven
This is not good use of a microwave: it cannot achieve the heat required to form a diamond.
microwave Oven,griller, electrical stove
If the microwave is not energized, then the food will spoil. If the microwave is energized, then the food will burn.
It crackles and pops. You would probably have to get a new microwave if you attempted this at home.
no
microwave
nothing would happen the microwave does not know if there is anything in there or not.
Nothing
Boom.