How do you make diamonds?

Answer 1

Diamond can be made when carbon atoms are compressed at a very high temperature and pressure. This occurs naturally with carbon deposits (like prehistoric swamps) that are buried deep enough in the crust to be subjected to sufficient high temperatures and pressures. Most diamonds are dug out of the ground, having been produced by geological processes.

It is possible to manufacture REAL carbon crystal diamonds, but it isn't something you will be doing in your backyard anytime soon.

There are several ways this can be done. Just as natural diamonds, synthetic diamonds are created using high pressure and high temperature (HPHT). This can be done with a shaped high explosive charge or more commonly through multimillion dollar, purpose built machines: the belt press, the cubic press, or the split-sphere press (sometimes called a BARS apparatus). The machines generally yield much higher purity diamonds than the explosive method (this has been demonstrated on the Discovery Channel show Mythbusters). REAL diamonds can also be made using Chemical Vapor Deposition, where the diamond is grown gradually by feeding varying amounts of hydrocarbon gases into a chamber and energizing them. The gases are ionized into chemically active radicals in the growth chamber using microwaves, hot filament, arc discharge, welding torch, laser, electron beam, or other means. The diamond is grown one carbon atom at a time as the carbon radicals attach themselves to the substrate of existing carbon crystals.

On the microscale, diamonds may be formed using ultrasonic cavitation and at room temperature, but these are too small to be viewed with the naked eye.