Database of luminescent Minerals


Chemical Formula: Al2O3

Familly: Oxides and hydroxides

Status: IMA-GP

Crystal System: Rhomboedric

Mineral for Display: Yes

Associated names (luminescent varieties, discredited names, synonymes etc.):  Rubysapphire


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Red Very StrongVery often
Mid waves (320 nm):      Red
Short Waves (254 nm):      Red MediumOften
Other colors LW:          
Violet red , Violet Pink ,
Other colors SW:     
Orange ,

Long Waves Picture (365nm)

Rubis, UV LW,
Sivec Marble Quarry, Sivec Mountain, Prilep, Macedonia
Photo & Col. G. Barmarin

Short Waves Pictures (254nm)

Rubis, UV SW,
Mysore District, Karnataka, India
Photo & Col. © G. Barmarin


Phosphorescence (in the common meaning of the term) seen by naked eye:

No phosphorescence seen by naked eye whatever the type of UV


Ruby variety(red): almost always luminescent(Cr3+)
sapphire variety (blue): sometimes weak red or pink luminescence
Other colored sapphires: frequently luminescent with variable intensity.

Main Activator(s) and spectrum:

Most Common Activator: Cr3+

Peaks in the spectrum (nm):

Cr3+ replacing Al : Lines at 692.8, 694.3nm  (R1 and R2 lines)

Cr3+ :  658.2 , 668.2 ,  674.1 , 680 (small lines)  

N-lines (Cr3+ pairs) : 705.8 , 712nm (small lines)

Fe3+ : broad band peaking at 896nm (Sapphire)

No spectrum for the moment

Comments on activators and spectra:

Crookes (1887) and Becquerel (1861) considered pure alumina as fluorescent; but De Boisbaudran (1887) stated that chromium as impurity was the cause of the fluorescence.


Bois and Elias (1908) studied the effect of low temperature and magnetic field on several chromium salt and ruby in particular.


Steady-state luminescent properties of natural corundum Al2O3 were carefully investigated.


Activator: Cr3+ replacing Al giving strong well known 2E->4A2 lines with long decay time

Besides that, much weaker narrow lines present, which are connected with Cr-pairs and more complicated complexes (so called N-lines) (Tarashchan 1978).



Cathodoluminescence: red or light-blue (undetermined origin);


The weaker peaks from the long wavelength side of the principal lines are also known and ascribed to so call N-lines, namely Cr3+ pairs.


Best Locality for luminescence(*):

(*)Data are not exhaustive and are limited to the most important localities for fluorescence

Bibliographical Reference for luminescence:

Luminescence Reference on internet:

Mineralogical Reference on internet:

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Note: While all due attention has been paid to the implementation of the database, it may contain errors and/or accidental omissions. By nature, the database will always be incomplete because science always evolves according to new analysis.
A request providing no result means only that no such reference exists in the database, but it does not mean that what you are looking for does not exist, just not to our knowledge. If you think you have found an error or omission, please let us know via the contact page being sure to cite the source of information.


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