The principle of the process involves melting a finely powdered substance using an oxyhydrogen flame, and crystallising the melted droplets into a boule.
There have been examples of oxyhydrogen cutting sets with small (scuba-sized) gas cylinders worn on the user's back in a backpack harness, for rescue work and similar.
An intense illumination is created when an oxyhydrogen flame is directed at a cylinder of quicklime (calcium oxide), which can be heated to before melting.