Hello, I had heard of irradiating poorer quality aquamarine to turn it a deeper blue. I did not know they took the clear stones and sold them that way. They used to do the same thing with Utah topaz. The sun fades them to clear. A little radiation brings out the color.
It is quite rare for Aquamarine to go darker Blue on irradiation,but
some small percentage does.It is differerent than natural Blue
Aquamarine in the Dichroism.It is more intense and reverse from the
natural,down the “C” axis can be dark Blue while your “A” axis can be
a muddy Blue to Yellowish.Although most are stable,some fade and have
come to be known by the name of one mine notable for
fading;“Maxixe”.Most Aquamarine depending how it is irradiated will go
to yellow to Golden to even a dark Orange resembling Imperial Topaz.
Not certain about Utah Topaz,a natural coloration of peachy brown,but
I think might be similar to the Mexican material that occurs the
same.If so,I caution against irradiating them.The Mexican becomes
reactive,and can have half life of hundreds of years. Mark Liccini