Gemological and Spectral Characteristics of Gem-Quality Blue Gahnite from Nigeria

Table 5

Comparison of different Cr³⁺-activated spinel photoluminescence spectra (650∼750 nm) (nm).

Species	650∼680	680∼690	690∼702	702∼712	712∼725	Source
Natural gahnite	675.3	686.3 (R)	693.8, 697.9	708.5	717.6	This work
Natural spinel	672, 674, 675	685.6 (R), 686, 687, 689	695, 698, 700	705, 707, 709	717, 722	[21]
Natural spinel	677	685 (R)	697	710	718	[19]
Natural spinel	666, 676	686 (R)	698	708	717, 723	[23]
Identification		R/N-line	R-PSB