As early as 1694, Florentine academicians suspected that diamond was made of carbon when they found that the precious stone could be burned completely in air. In 1772, this speculation was confirmed by the French chemist Antoine Lavoisier who discovered that the gas released from a burnt diamond was indeed carbon dioxide. Kimberlites are derived from ascending mantle plumes that rise to release heat. While they move upward, they may melt due to the reduction of pressure. The volume of magma will rapidly increase so it may extrude to the surface. If the rising kimberlite flows across the region where diamonds are located, it will carry them up to the surface. Numerous methods using high pressure technology have been invented to synthesize diamond. In fact, high pressure technology was developed largely because of the need to synthesize diamond. On December 16, 1954, Tracy Hall of General Electric Company in the United States also was successful in synthesizing diamond.