Synthetical formation of diamonds As everyone knows a diamond won't last forever. It will eventually turn into a graphite over a long period of time, as the free energy of graphite is lower than that of diamond, hence making the reaction energetically favorable. 

However, is it possible to do the reverse, by using graphite and the applying energy onto graphite so as to synthesize diamond. If so, how is it done and can it be done in a lab by a chemist? Does that mean that people who managed to do it can become rich? As a diamond costs so much more than a graphite. Shouldn't we synthesize diamonds in this way? Can I become  rich by synthesizing diamonds and selling them?
Natural Diamonds are formed under high pressure and temperature at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites.

According to Wikipedia,


  The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 kilobars (4.5 and 6 GPa), but at a comparatively low temperature range between approximately 900 and 1,300 °C (1,650 and 2,370 °F). These conditions are met in two places on Earth; in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike.


So yes, Diamonds can be produced synthetically if you can simulate almost similar conditions as in Earth's Mantle. (See high-pressure high-temperature process; Synthetic Diamond) An alternative, and completely different growth technique is chemical vapor deposition (CVD).