事实上,4C只是鉴定钻石的基本指标。要想细致的鉴别钻的好坏,除了以上的4C,我们还有关注以下几个指标。

GIA国际认证的钻石最佳比例标准(“严选”是指钻石的最理想黄金比例):

1.Total Depth Percentage深度比例:57.5%-63%,严选60%-62.3%

2.Table Size 桌面比例:52%-62%,严选54-58%

3.Crown Angle 冠部角度:31.5-36.5°,严选34-35°

4.Crown Height 冠部高度比例:12.5%-17%,严选 15-15.5%

5. Pavilion Angle 底部角度: 40.4-41.8°,严选40.5-41°

6.Pavillion Depth 底部深度比例: 42.5-44.5%,严选42.5-43.5%

7.Star Facet Length Percentage 星形刻面长度比例:45%-65%,严选50-55%

8. Lower Girdle Facet Percentage 腰下刻面比例:70%-85%,严选75%

9.Girdle Thickness 腰围厚度:Thin,Thin to Medium.,Thin to Slightly Thick,Medium,Medium to Slightly Thick,Slightly Thick共六种, 严选 Thin to Medium, Medium, Medium to Slightly Thick这三种

10.Culet Size 底尖大小:None-very small,small,严选None

11.Polish 抛光:Very Good or Excellent,严选Excellent

12.Symmetry对称性:Very Good or Excellent,严选Excellent