The color of fine gold shows paradoxical variations that have tentatively been explained by metallurgic factors. Measurements and digital photographs show a significantly redder color than predicted by theory. A novel purely optical explanation based on the multiple reflection in grooves is suggested. The analysis in the colorimetric space RGB of the photographs of several fine gold samples and coins confirms that the gold red shift comes from minute grooves that seem black but that in fact have an extremely dark orange/red color.

中文翻译：

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金的红移：凹槽中多次反射的色度

纯金的颜色显示出矛盾的变化，这些变化暂时可以用冶金因素来解释。测量和数码照片显示的颜色比理论预测的要红得多。提出了一种基于凹槽多次反射的新型纯光学解释。对几个纯金样品和硬币的照片在比色空间 RGB 中的分析证实，金红移来自看似黑色但实际上具有极深橙色/红色的微小凹槽。