Variety ruby
Origin: Karnataka State, India
Owner: Axel Emmermann
Corundum (variety ruby) under LW-UV light
Origin: Karnataka State, India
Owner: Axel Emmermann
Ruby is a variety of corundum that contains trace-amounts of chromium. The chromium causes the red color of ruby in plain light as well as its red fluorescence.
Origin: Priler, Macedonia (former Yugoslavia)
Owner: Axel Emmermann
This 'ruby' is pinkish and opaque in normal light en should therefore be regarded as corundum rather than ruby. The bright red fluorescence, on the other hand, reveals the presence of chromium (the activator) which is exactly the ingredient that turns corundum into ruby. The orange fluorescing spot is quite unusual for ruby (or corundum). The crystal was extracted from its calcite matrix by means of a strong acid (blue-white fluorescing remnants of the matrix are still visible on the image).
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