The concept of compressing soft materials to very high pressures between two opposed anvils was developed a century ago by Bridgman at Harvard University. But it was not until 1959 that diamonds were used as the anvil material, even though diamond’s unique properties, such as extreme hardness and transparency to light and X-rays, had been known for a long time. The first diamond anvil apparatus was constructed at the National Bureau of Standards in Washington, DC by Weir and Van Valkenburg 1 and by Jamieson and colleagues at the University of Chicago 2 . It was developed further by Peter Bell and Ho-Kwang Mao at the Carnegie Institution and Arthur Ruoff at Cornell University. Even in these early studies, pressures of several hundred thousand atmospheres could be generated at room temperature, and it was immediately clear that under such high pressures fundamental changes in the physical behavior of materials were to be expected. At that time, nobody dreamed of converting a noble gas like Xe into a metal at a pressure just above a megabar 3,4 . Then, about 30 years ago, Bassett and coworkers 5 introduced laser heating to the diamond cell and opened an even larger field of research, including the study of phase behavior, chemical reactions, material synthesis, and mineral and metal properties under conditions found in planetary interiors. A general objection to using diamond anvils as a synthesis tool is the extremely small yield. However, one should keep in mind that, when diamonds were first synthesized at high by Reinhard Boehler Diamond cells and new materials Max-Planck-Institut für Chemie, P.O. Box 3060, 55020 Mainz, Germany E-mail: boe@mpch-mainz.mpg.de November 2005 34 ISSN:1369 7021 © Elsevier Ltd 2005 The diamond anvil apparatus, invented nearly 50 years ago, has developed into a versatile tool for a broad spectrum of high-pressure research topics, ranging from low-temperature physics to high-temperature geoscience. It is superbly suited for high-pressure and high-temperature synthesis because new materials can be identified and characterized in situ. The combination of high pressure and high temperature, generated by two opposed diamond anvils and infrared (IR) lasers, respectively, has allowed the simulation of the extreme conditions of planetary interiors, the discovery of new structures and behavior in elements, and the synthesis of novel hard materials. Here, we describe the relatively simple technique of generating and controlling high pressure and high temperature, and present recent examples related to these topics.