Spectral data was obtained with SF-56A spectrophotometer in the 370 - 770 nm range, 1 nm step in Moscow State University Gemological Center. Spectra were recorded through two opposite parallel windows of the sample in room temperature.
All spectral data recorded on the spectrometer were converted into an adsorption coefficient in mm-1 taking into consideration the thickness of the sample and the refraction coefficient of the gem material. All spectral data for natural (untreated) colored diamonds was averaged with 20 nm step.
A Prism model with similar thickness as used for spectral data collection was selected in DiamCalc (for polished stones - Helium scanned 3D model of radiant cut). Light conditions for the prism in DiamCalc files: one transmitted source type A (for polished stones 3D models: the standard Dialite DiamCalc lighting).
Corresponding absorption spectra used for modeling are available in the Microsoft
Excel format.
Amethyst
Amethyst violet new! A moderate violet natural amethyst spectrum obtained through 10 mm thick plate along an arbitrary direction.
Corundum Red irection 2
Spectrum of the same red material obtained through the 11 mm thick plate with another arbitrary direction. Red color of that stone is related with Cr3+ adsorption features.
Corundum Orange Red direction 2
Spectrum of the same material obtained through the 11.5 mm thick plate along another direction. Cr3+ features also present in spectrum of this stone, but the concentration of Cr is much lower.
Corundum Orange direction 2 Spectrum of the same material obtained through the 10 mm thick plate along another direction. No Cr3+ related features present. Color origin of that stone is undefined.
Cubic Zirconium Yellow new! A yellow cubic zirconium (CZ) spectrum obtained through 4 mm thick plate. Color of that stone is related with REE adsorption.
Diamond Dark Orange Brown A dark orange-brown natural diamond (untreated) spectrum obtained through 3.6 mm thick plate. This diamond is Ia type and it can be assumed that its color is connected with dislocations.
Diamond Fancy Deep Orange Brown A fancy deep orange-brown natural diamond (untreated) "Diamond_Fancy_Deep_Orange_ Brown" spectrum obtained through 4.15 mm thick plate. This diamond is Ia type and it is assumed that its color is also connected with dislocations.
Diamond Fancy Yellow A fancy yellow natural diamond (untreated) spectrum obtained through 4 mm thick plate. This diamond is natural Ib type and its color is related with C-centers absorption.
Diamond Fancy Yellow Lemon A fancy greenish-yellow natural diamond (untreated) spectrum obtained through 6.76 mm thick plate. Color of that stone is related with two broad bands on 478 and 560 nm.
Diamond Yellow new! A light yellow natural diamond spectrum obtained through 3.5 mm thick plate along an triad axis direction. This diamond is Ia type and its color is related with N3-N2 centres.
Sapphire new! A blue natural sapphire "Sapphire" spectrum obtained from Mineral Spectroscopy Server visible spectra database* and then adjusted. Sapphire color is related with Ti-Fe presence.
Yellow synthetic diamond A yellow synthetic diamond spectrum obtained through 5 mm thick plate. This diamond is Ib type and its color is related with C-centers absorption.
Quartz through the zone with weaker color A yellow color-treated natural quartz spectrum obtained through 12 mm thick plate perpendicular C-axis of the stone recorder through the zone with weaker color.
Quartz through the zone with more yellow color Spectrum of the same material obtained through the same plate but through the zone with more yellow color. Color of that stone is related with Fe3+ presence.
