不同模拟光源下圆明亮型钻石亮度的研究

Brilliance of Round Brilliant Diamond under Different Simulative Light Sources

钻石的光学效果是钻石品质和价值的直观体现,不同光源照射下,钻石呈现的光学效果有很大的差异。为了综合评价钻石光学效果的优劣,设计珠宝店照明模拟光源和钻石灯模拟光源,采用钻石光学效果观察仪对48颗不同切工的钻石进行明亮图案采集,研究切工参数变化对钻石的亮度和亮度图案的影响。研究表明:在相同的光源下,相同亭角、不同冠角的钻石光学效果图有很大的差异,相同冠角、不同亭角的钻石光学效果图差异也很大,即使冠角和亭角相差不大,其最终的光学效果变化很大。在不同的光源下,同一样品所表现出的明亮图案和亮度值有较大的差异,但钻石的亮度值随冠角和亭角的变化趋势几乎一致,高亮度的钻石和低亮度的钻石具有相似的冠角和亭角组合。切工等级低的钻石在合适的冠角、亭角组合下,其亮度有的比切工等级高的钻石的亮度好。但是从明亮图案的分布上来看,切工等级较高的钻石,其明亮图案分布较佳。高亮度钻石的冠角和亭角有相关性,线性回归关系:α+0.167β=44.5°(α为亭角,β为冠角)。因此,在一定的范围内,增大亭角同时减小冠角,或者减小亭角增大冠角,可得到圆明亮型钻石最佳的亮度效果。

The visual properties of diamonds are the intuitional reflect of diamonds’quality and value.Under different light sources,the visual properties presented by diamonds are very different.In order to comprehensively evaluate the visual properties of diamonds,the authors designed simulative jewelry store illumination light source and simulative diamond grading lamp light source.The instrument for observing diamond visual properties was used to capture diamond actual image patterns and 48 diamond samples with various cuts were analyzed.The effect of diamond cut parameters on the brilliance was studied.Results of the experiment indicated that the visual properties presented by various diamonds are quite different under the same incident angle light source even if the differences of diamond cut parameters are small.Under the different light source,the bright image pattern and brightness values of the same sample showed great differences,but the changing tendency of the brightness values along with diamond crown angle and pavilion angle were similar.Diamonds with high brightness or low brightness had similar crown angle and the pavilion angle combination.By analyzing the trend of the brilliance under the different light sources,it was indicated that the brilliance of the diamond is not positively related to the cut level of the diamond.The brilliance of the diamond with low cut level may be better than that of diamond with high cut level.That is to say,the brilliance of the diamond can not be determined based on the cut level alone,but it can be confirmed that the overall light pattern of the diamond with the higher cut level is more uniform and beautiful than that of the lower cut level.Crown angle and the pavilion angle have relevance relationship for the diamond with good brilliance.Based on the diamond crown angle and the pavilion angle combination,the authors built a linear relationship:α+0.167β=44.5°(αis for pavilion angle andβis for crown angle).In conclusion,in a certain range,increasing pavilion angle and at the same time reducing the crown angle,or reducing pavilion angle and at the same time increasing the crown angle,the brilliance of the round diamond can obtain a good performance.