Trace impurity ions Cr³⁺ and V³⁺ in emerald both absorb visible light in the red and blue-violet range, giving rise to the emerald's green color. The Cr³⁺ impurity can also luminesce in the visible red when illuminated with laser light. We have shown that peak positions and relative intensities of R lines appearing in the photoluminescence spectrum of emerald depend upon the emerald's origin. In particular the R₁ line of lab created emeralds is positioned at the shortest wavelengths, while for natural emeralds with a non-schist origin this line is found at the same or longer wavelengths, and for natural schist origin emeralds this line peaks at even longer wavelengths.¹ Recently we have learned that the R₁ line's peak position depends upon concentrations of trace impurities Mg²⁺ and Na⁺ in the emerald, and that the less common shifts of the R₂ line's peak arise from increased concentrations of the trace impurity Li¹⁺.