| 摘要 |
PROBLEM TO BE SOLVED: To easily manufacture a cover-ring-fixed jewels such that a gem can be fixed in position by means of a thinly formed cover ring without losing its brightness. SOLUTION: A method of manufacturing the cover-ring-fixed jewels comprises: a first process for attaching to the chuck part of a lathe the rear end of a short cylinder formed with a collet having an increased diameter at approximately its inner end and adapted for supporting the gem; a second process for seating the desired gem on the collet and pressing the table surface of the gem by means of the end of a pressing jig attached to a tail stock, so as to fix the table surface to the short cylinder; a third process for causing the outer peripheral part of the collet located on the girdle face of the gem to be pressed by a first pressure roller in a centripetal direction, while rotating the lathe; a fourth process for pressing the end of the collet by means of a second pressure roller along the crown face of the gem in the direction of inclination; and a fifth process for forming a cover ring part by cutting into a certain width, using a cutter, the vertically pressed part of the collet pressed and deformed during the third and fourth processes, the vertically pressed part abutting against the girdle face of the gem.
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