Study On Optical Effect Of Non-fancy-color Round Brilliant Cut Diamonds And Synthetic Ruby

The scintillation of non-fancy-color round brilliant diamonds and the optical effect of faceted synthetic ruby were evaluated.A method for quantitatively evaluating the diamond scintillation was proposed: The scintillation of non-fancy-color round brilliant diamonds under D65 illumination was evaluated quantitatively via the entropy method with the CIE DE2000 color difference formula.The results were verified by naked eye.The evaluation results of the two were51.51% at the same level,and 92.42% were at most one level different.The brightness,chroma and hue of the diamond were significantly affected the scintillation and brightness was the main factor.When the diamond scintillation strongly,its visual weight was greater than its actual weight.According to the weight estimation formula of the non-fancy-color round brilliant diamond,the overflow coefficient K and the overflow weight ?W of the diamond were calculated.When the diamond carat weight W?(0.10 ct,4.95 ct),the diamond semi-diameter SD?(1.5 mm,5.5 mm),the overflow semi-diameter ?SD?(0.10 mm,0.22 mm),the overflow coefficient K?(0.03,0.32),and the overflow weight ?W?(0.01 ct,0.41 ct).The visual weight was increased by 3.00%-32.00%compared with the actual weight.The optical effect of oval faceted synthetic ruby,that was,the color change during rotation,was evaluated via the entropy method.The synthetic ruby was different from non-fancy-color diamonds,and it had obvious dichroism—rose red /orange red.In the directions of 0°,30°,60°,90°,120°,and 150° with the pear crystal's cross-sectional,the faceted synthetic rubies and the plane synthetic rubies were cut with the same angle,respectively.When the plane synthetic ruby was 90°with the direction of pear crystal's cross-sectional,displayed the weakest dichroism;when the plane synthetic ruby table was 150° with the direction of pear crystal's cross-sectional,displayed the strongest dichroism.After the synthetic ruby was cut,the synthetic ruby at different angles to the pear crystal's cross-sectional could exhibit dichroism.The color of the faceted synthetic rubies and the plane synthetic rubies atsame angles to the pear crystal's cross-sectional were measured by the colorimeter,and the corresponding color difference were calculated which were between 10 and14.The optical effect of oval faceted synthetic ruby was mainly affected by chroma,followed by lightness,and hue had the least effect.The diamond belonged to the cubic crystal system,and the table could be in any direction when it was cut,regardless of factors such as maintaining maximum weight.But when the synthetic ruby was cut,the table should avoid 30? with the direction of pear crystal's cross-sectional.In this direction,using entropy method to evaluate its optical effect had the highest score,that was,the chroma changed the most.This direction was also the direction of the strongest dichroism displayed by faceted synthetic ruby,and the direction had the largest color difference between the plane synthetic ruby and faceted synthetic ruby.But this direction was not the direction of the synthetic ruby's optical axis.The result be related to the cutting ratio of synthetic ruby.