| 摘要 |
FIELD: production of jewelry articles, in particular, cutting of diamonds and precious stones. ^ SUBSTANCE: diamond cutting form has crown portion arranged in upper part and rim portion arranged in lower part of form. Rim portion angle "p" is within the range of from 45 deg to 37.5 deg, angle "c" of crown portion is in the range satisfying the condition: -3.5 x p+163.6 >= c >=-3.8333 x p+174.232. Angle "c" of crown portion and angle "p" of rim portion are set in such a manner that light beams entering crown portion facets and exiting crown portion facets, light beams entering flat facet and exiting crown portion facets, and light beams entering crown portion facets and exiting flat facet are simultaneously oriented toward observer. According to preferable version, angles defined by incident light beams and exiting light beams are substantially equal to one another. Diameter of flat facet is between 0.60 and 0.33 or is equal to said values; according to preferable version, said diameter must not exceed 0.55 and according to most preferable version, said diameter must not exceed 0.38 the diameter of equator. ^ EFFECT: improved brightness and glittering of diamonds and precious stones. ^ 19 cl, 27 dwg, 2 tbl |
