| 摘要 |
An apparatus is described for producing concave or convex optically magnified facets about a gem, each facet being a curved surface that is a section of a cylinder. It utilizes a mandrel having an exterior and/or interior cylindrical abrasive surface. The surface is contacted by a gem indexed and adjustably held by a gem support structure. The mandrel is angularly movable about its central axis. It can also be reciprocated along the axis to prevent formation of random striations across the facet surfaces. An adjustable stabilizer can be preset to engage a dop attached to a gem at a location adjacent to the mandrel. This assures accurate reengagement of the gem after movement from the mandrel for interium inspections during the faceting precedure. The method of producing the optically magnified facets requires successive indexing of the gem and bringing it into contact with an angularly moving cylindrical abrasive surface. The resulting gem can have one or more curved facets about its outer surfaces having the form of a section of a cylinder. These facet surfaces can be either concave or convex. A preselected pattern of grooved facets can be produced across the curved facets by polishing then against a complementary moving mandrel surface.
|
