Abstract: A coated particle for synthesizing diamond includes: a single crystal of a fine diamond particle coated with at least one layer which contains at least one kind of solvent metal powder for synthesizing diamond and/or at least one kind of solvent metal powder with organic bonding material. Diamond abrasive particles for sawing are produced by a process which includes the steps of: coating fine diamond particles with at least one layer which contains at least one kind of solvent metal powder for synthesizing diamond and/or at least one kind of solvent metal powder with organic bonding material, filling a molding with the coated fine diamond particles, compacting, arranging a compact in a synthesizing vessel, heating the compact to a temperature above a solvent metal-graphite melting point under a pressure condition in which diamond is thermodynamically stable, and recovering the diamond abrasive particles.

Abstract: An infrared optical part comprised of a synthetic diamond single crystal, and a method of making the same. The infrared optical part is comprised of a synthetic diamond having a nitrogen content of not more than 5 ppm and a boron content of not more than 3 ppm, wherein the parallelism between its light incident and reflecting surfaces is not more than one minute. The infrared optical part is used as a window member in infrared spectral analysis. It is also used in the form of a pair of anvils for holding a sample therebetween in connection with the measurement of transmitted light that has passed through the sample after the sample is compressed. The part is also used in the form of an infrared ATR prism.