Visible adsorption spectra and DiamCalc-files of colored gem materials

Sergey Sivovolenko, OctoNus
Yuri Shelementiev, Diamond Design
Roman Serov, Moscow State University Gemological Center

Colored gem materials:

• Amethyst
• Corundum
• Cubic Zirconium
• Diamond
• Emerald
• Sapphire
• Synthetic diamond
• Topaz
• Quartz

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.  amethyst_prizm.dmc  amethyst.xls  amethyst.dmc   Corundum Corundum Red direction 1 A red synthetic corundum spectrum obtained through 10 mm thick plate along an arbitrary direction.  Corundum_Red_direction1_prizm.dmc  Corundum_Red_direction1.xls  Corundum_Red_direction1.dmc   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_Red_direction2_prizm.dmc  Corundum_Red_direction2.xls  Corundum_Red_direction2.dmc   Corundum Orange Red direction 1 An orange-red synthetic corundum spectrum obtained through 10 mm thick plate along an arbitrary direction.  Corundum_OrRed_direction1_prizm.dmc  Corundum_OrRed_direction1.xls  Corundum_OrRed_direction1.dmc   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_OrRed_direction2_prizm.dmc  Corundum_OrRed_direction2.xls  Corundum_OrRed_direction2.dmc   Corundum Orange direction 1 An orange synthetic corundum spectrum obtained through 9 mm thick plate along an arbitrary direction.  Corundum_Or_direction1_prizm.dmc  Corundum_Or_direction1.xls  Corundum_Or_direction1.dmc   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.  Corundum_Or_direction2_prizm.dmc  Corundum_Or_direction2.xls  Corundum_Or_direction2.dmc   Cubic Zirconium Cubic Zirconium Green A green cubic zirconium (CZ) spectrum obtained through 18 mm thick plate. Color of that stone is related with REE adsorption.  CZ_Green_prizm.dmc  CZ_Green.xls  CZ_Green.dmc   Cubic Zirconium Red A red CZ spectrum obtained through 20 mm thick plate.  CZ_Red_prizm.dmc  CZ_Red.xls  CZ_Red.dmc   Cubic Zirconium Violet A violet CZ spectrum obtained through 22 mm thick plate. Color of that stone is related with REE adsorption.  CZ_Violet_prizm.dmc  CZ_Violet.xls  CZ_Violet.dmc   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.  CZ_Yellow_prizm.dmc  CZ_Yellow.xls  CZ_Yellow.dmc   Diamond 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_Dark_OrangeBrown_prizm.dmc  Diamond_Dark_OrangeBrown.xls  Diamond_Dark_OrangeBrown.dmc   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_DeepOrBr_prizm.dmc  Diamond_Fancy_DeepOrBr.xls  Diamond_Fancy_DeepOrBr.dmc   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_prizm.dmc  Diamond_Fancy_Yellow.xls  Diamond_Fancy_Yellow.dmc   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_Fancy_YellowLemon_prizm.dmc  Diamond_Fancy_YellowLemon.xls  Diamond_Fancy_YellowLemon.dmc   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.  Diamond_Yellow_prizm.dmc  Diamond_Yellow.xls  Diamond_Yellow.dmc   Sapphire 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.  Sapphire_prizm.dmc  Sapphire.xls  Sapphire.dmc   Emerald Emerald new! A green natural emerald spectrum is one of DiamCalc standard spectra. Emerald color is related with Cr presence.  Emerald_prizm.dmc  Emerald.xls  Emerald.dmc   Synthetic diamond 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.  Synthetic_diamond_Yellow_prizm.dmc  Synthetic_diamond_Yellow.xls  Synthetic_diamond_Yellow.dmc   Topaz Topaz parallel C-axis direction A blue irradiated topaz "Topaz_paralC" spectrum obtained through 13 mm thick plate along parallel C-axis  Topaz_paralC_prizm.dmc  Topaz_paralC.xls  Topaz_paralC.dmc   Topaz perpendicular C-axis direction Spectrum of the same material obtained through the 11.5 mm thick plate in the perpendicular C-axis direction.  Topaz_perpC_prizm.dmc  Topaz_perpC.xls  Topaz_perpC.dmc   Quartz 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.  Qtz_Yellow_weak_perpC_prizm.dmc  Qtz_Yellow_weak_perpC.xls  Qtz_Yellow_weak_perpC.dmc   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.  Qtz_Yellow_intence_perpC_prizm.dmc  Qtz_Yellow_intence_perpC.xls  Qtz_Yellow_intence_perpC.dmc

All spectral data recording, calculations and DiamCalc modeling done at Moscow University (MSU) Gemological Center