圆明亮琢型的上、下腰刻面倾角在GIA新切工标准中“EX级”的规范

“EX Level”Specification on Inclination of Upper and Lower Girdle Facets of Round Brilliant Cut in New GIA Cut Standard

摘要: 上腰刻面和下腰刻面的倾角是圆明亮琢型宝石切工中两个重要的参数。本文对美国宝石学院（GIA）新切工标准中“EX级”的上、下腰刻面倾角加以规范，并运用数学方法和计算机软件（Pro/E、Matlab和MathCAD）对规范进行可视化处理；最后对相关文献提供的样品数据进行可视化、参数化处理。这种方法对圆明亮琢型宝石的设计、加工和成品检测都具有指导意义。

Abstract: Inclinations of upper girdle and lower girdle facets are two important parameters of round brilliant cut.This paper provides specifications on inclinations of upper girdle and lower girdle facets for Gemological Institute of America（GIA）“EX level”.Furthermore，the specifications are visual by mathematical methods and computer software（e.g.Pro/E，Matlab and MathCAD）.Finally，some data of sample provided by the relevant literature are visualized and parameterized.The method has guiding significance for the design of round brilliant cut gemstone，processing and testing the finished product.