Is turning graphite carbon into diamond industrially doable?
It has been done since 1954 and has been a commercial success for some time. Many products now have diamond-like coatings, produced comparatively inexpensively through vapor deposition without need for high pressure.

BTW, in English "burning" means to set on fire, oxidize; I believe you mean "heating graphite", and, as your graph shows, pressure is needed as well as heat.