The family-owned firm Pureon, headquartered in Switzerland, is one of the leading suppliers of precise, diamond-based, polishing abrasives on the planet.
Graphite powder is subjected to massive, controlled explosions in Smithfield, Pensylvania, which produce the heat and pressure required to convert the crystalline allotrope form of carbon that graphite is composed of into the diamond cubic crystalline form of carbon that constitutes diamond. Once it has cooled, the fused core is sliced and soaked in acid to remove any residual graphite and other contaminants from the diamond. Back in Switzerland, the particles of pure diamond are put through a lengthy sequence of sedimentation and grading processes that, in turn, yield highly-refined diamond slurries with tightly-controlled specifications of either mono-crystalline or polycrystalline diamonds ranging in size from just under a millimeter to less than a nanometer.
Beyond supplying critical tools used in the manufacturing of watch components across the industry, Pureon also collaborates closely with fellow Swiss firms—like La Pierrette, who manufacture a sizeable portion of the Swiss watch industry's ruby bearings, pallet fork jewels, and roller jewels—to pioneer new manufacturing and finishing techniques through their Surface Lab.
The linked video provides an overview of their manufacturing stages, operations, and R&D facilities. Hat tip to Marc André Deschoux for shining a light on this keystone supplier of the Swiss watch industry.