Alexandrite Engagement Rings 17

         Alexandrite Rings.
By Aamir Mannan.              ALEXANDRITE
This is another typical chromium spectrum, with the lines more clearly defined  than in emerald - sharper perhaps even than in ruby. In alexandrite the central board absorption band which determines the colour is in a half-way position, centered at 


5800 A, compared with the red ruby and the green emerald - hence its balance of colour between green (daylight) and red (tunstun light). The strong doublet in the deep red is at 6803 and 6785 A, and its 'reversible' as in ruby, though not seen as a fluorescence line in ordinary circumstances. There are weaker lines at 6650,6550 and 6450 A. Narrow lines can be seen in the blue at 4730 and 4680 
A. There is sufficient resemblance with the ruby spectrum to cause possible error if the spectrum is only carelessly examined, and the stone itself accepted as ruby on its appearance in artificial light only.

A