31-1821-CO-PR-8451-16











Certificate number 31-1821-CO-PR-8451-16
Mineral Specie Corundum
Issue date 2016-05-11
Variety Ruby
OriginNatural - glass-filled treated
Chemical composition Aluminium oxide
Crystal system Rhombohedral
Habit Hexagonal prism with rombohedral faces
ColourAccording to GIA GEmSet: slpR 7/3 slightly purplish red, dar,very slightly grayish
Cutting StyleOval
Measurements4.82x2.66x7.20 mm
Weight2.34 ct
LusterVitreous
TransparencyTransparent
Refractive indices1.770 - 1.762
Birrefringence0.008
Optic sign-
Hardness9 Mohs
CleavageNone
Density4.02
Absortion spectra Due to chromic oxide
Picture
Spectra description Fines lines in red like a doublet at wavelengths 694 and 692 nm. A broad absortion area cutting out the yellow and most of the green, two fine lines in the blue and the violet too being absorbed.
Comments
This gem have been treated with glass fissure filling. Fissure filling material may be unstable to elevated temperatures and to chemical agents.
Special care should be taken when cleaning or reparing jewelry items set with fissure filled corundum.
Small rounded crystals altered by heating and colour flashes revealing the glass filled fractures. Darkfield illumination, 15X. Filling material concentrated along fissures. Darkfield illumination, 40X.
 
 



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