Can a diamond's color be simulated by only a surface coloring?

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SUMMARY

The discussion centers on the replication of the Hope Diamond's color through surface coatings applied to cubic zirconia (CZ) replicas. Experts from Azotic LLC utilized precious metal coatings to mimic the diamond's lush blue hue, but the underlying material properties of CZ, including its higher index of refraction, prevent it from achieving the same optical characteristics as natural diamonds. The conversation highlights that true color simulation requires internal material properties, such as the presence of boron in diamonds, rather than solely relying on surface treatments.

PREREQUISITES
  • Understanding of gemology and diamond characteristics
  • Familiarity with cubic zirconia and its optical properties
  • Knowledge of light refraction and wavelength attenuation
  • Basic concepts of semiconductor materials, specifically P-type semiconductors
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  • Research the optical properties of cubic zirconia versus natural diamonds
  • Explore the process of gem coating and its effects on color perception
  • Learn about the role of boron in diamond coloration and conductivity
  • Investigate gemological testing methods, including infrared absorption and conductance testing
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This discussion is beneficial for gemologists, jewelry designers, and anyone interested in the science of gem replication and optical properties of gemstones.

swampwiz
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I was reading this article about the a replica of the famous Hope Diamond and its antecedents:
https://www.nytimes.com/2020/11/28/style/hope-diamond-story-smithsonian-copy.html
This part seems to say that the color is to be simulated by a coating:
He strives to assure that his replicas have the exact same angles and color as their inspiration, a process that involved seven trips to Azotic LLC., a laboratory for gems and crystals in Rochester, Minn. There, experts coated and recoated the replica using a thick level of precious metals to match the lush blue of the Hope.
It would seem to me that the proper attenuation of wavelengths would need to be done via the body itself, not the surface. Of course, since the replica is cubic zirconia, the speed of light within the body will be a little off, so I guess it doesn't matter so much.
 
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Depends on how carefully it is examined. Natural clear quartz crystals with a coating of Amethyst (purple quart) shows the inner crystal up close but not discernible at arms length. The blue color of the Hope is traces of Boron in the Carbon, making it a giant P-type semiconductor. How is the coating going to glow red in the dark like the Hope diamond?
Gemologists, besides visually inspecting the diamond, check conductance and infrared absorption. CZ has a higher index of refraction and so obviously not a diamond.