Spinel Special Engagement Ring 8

Spinel Ring.

By Aamir Mannan.

 RED STONE

                 RED SPINEL (CHROA part from a broad absorption band in the green, centered at 5400 A bands or lines in spinel are rarely noticeable, through in chrome-rich types from burma a number of fine lines may be seen in the red. Red or pink spinels, however, can usually be determined with certainly on 

account of their very distinctive red fluorescence lines in the deep red. Unlike ruby, these form a group of five or more, reminiscent of a series of organ-pipes. Two central lines are brighter than the others strongest of all is that at wavelength 6860 A, which is separated by a dark gap from the next most prominent line at 6450 A. to see this distinctive series of lines clearly it is essential to use a really powerful light source. A copper sulphate filter is also 

very helpful as it shows the lines against a dark background. It is interesting to note that the seldom seen synthetic red spinels, whether made by the Verneuil process or by some other process of crystallisation, donot show the 'organ-pipe' structure, but have their red fluorescence chiefly centered in a single line at 6860A.When viewed through the spectroscope there is then a resemblance to ruby with these freak synthetic but absence of absorption 

bands in the blue is a sure sign that they are not ruby.