In the Middle Ages, alchemists tried to turn lead into gold. Lead was an inexpensive metal, while gold was and remains very valuable and a traded commodity. Success meant creating wealth. Similarly, scientists made serious efforts to imitate the natural process that creates diamonds. In the late 19th century, some of these efforts garnered some success. However, the important breakthroughs came only in the mid-20th century at the labs of General Electric in New York, where the first High Pressure High Temperature (HPHT) machine was invented by Tracy Hall.