Provided is a nanodiamond dispersion composition having excellent dispersibility of nanodiamond particles in an organic dispersion medium even when the organic dispersion medium has a small SP value. The nanodiamond dispersion composition according to an embodiment of the present invention includes an organic dispersion medium, nanodiamond particles dispersed in the organic dispersion medium, and a fatty acid ester dispersing agent. The fatty acid ester dispersing agent preferably has a mass loss rate of 20% or less when held in an air atmosphere at a temperature of 200 C. for 180 minutes. The fatty acid ester dispersing agent preferably has an acid value of 40 mgKOH/g or less.

The present disclosure provides a processing method of suspension abrasive jets, and the method comprises the following steps. Provide a workpiece on the processing machine. A suspension abrasive containing a plurality of abrasive particles with the same electrical property is provided in an abrasive suspension container. A non-aqueous fluid is supplied to the abrasive suspension container from a high pressure source. The workpiece is machined by jetting a suspension abrasive jet that couples a suspension abrasive and the non-aqueous fluid from a nozzle. The suspension abrasive and the non-aqueous fluid of the suspension abrasive jet are respectively recycled to the abrasive suspension container and the high pressure source by an abrasive separation and recycling device after the process.