You make CVD diamonds by growing them, and it takes about a day. That's right, a day to grow your very own bling. But you probably won't be doing that, unless you can duplicate the scientific process called Chemical Vapor Disposition which makes diamonds grow from seeds.
Protect yourself by wearing a contaminant control outfit including goggles, a hair cap and boots.
Place a diamond seed crystal in the CVD reactor. (It's okay to use a synthetic diamond.)
Inject methane and hydrogen gas to flow through the chamber.
Produce heat in the chamber with a microwave-generated plasma or a hot filament to cause the hydrogen gas to split into atomic hydrogen, which will then react with the methane. This will free carbon to form a plasma cloud.
Wait for the plasma cloud to rain carbon onto the diamond wafers or seeds.This will form new diamond bonds, carbon to carbon.
Allow the diamond wafer seeds to gradually grow into diamond minibricks. Every day, they will build up about a half a millimeter.
Remove diamond minibricks from the chamber. Slice them into wafers for industrial use as semi conductors or cut gems and polish them for use in jewelry.