but the most likely scenario is that "silky aquamarine" is actually
what is know as black beryl. Black beryl gets its color from micro
inclusions of black spinel which oriented along the plains
perpendicular to the optical axis. Black colour is observed only
in the center of such crystals. The surface of the crystals, can be
few inches deep, is grayish-blue and if cut would produce something
which can be called "silky aquamarine". Strictly speaking, it
should never be called and aquamarine.
While I’m deeply respectful of Mr. Surpin’s opinions, which are
generally right on the mark, I’ve cut some material like that, and it
certainly didn’t appear to be included with anything black. The
“silky” inclusions permeated the crystal toward the base - it was
clear at the tip, and it wasn’t any blacker in the center than on the
outside. The whole thing was the light-blue color typical of
aquamarines, without a grayish hue. Personally, I thought it made a
more interesting cabochon than the clear material, since it exhibited
chatoyance in strong light. The fibers looked a lot like the “silk”
found commonly in star sapphires, which I believe is caused by
rutile, not spinel. I’m not sure if it’s more or less valuable than
equivalantly-colored clear material, but since aquamarine is pretty
common stuff anyway, I’m not sure the difference was significant. The
customer who got it in a custom brooch seemed to like it a lot…
The "silky" inclusions permeated the crystal toward the base - it
was clear at the tip, and it wasn't any blacker in the center than
on the outside. The whole thing was the light-blue color typical of
aquamarines, without a grayish hue.
I am sure there are many different possibilities. I made a guess
based on the assumption that miners always want to reuse leftovers.
So this seems like a logical choice. When you have a crystal and you
have to chip away stuff to get to the valuable rough, it is easy to
see how an idea to sell the discarded rock might crop into the
someone’s mind.
Another point I want to make clear. Sometimes the comments are made
on the quality of gem material. Such comments should never be taken
as disparagement of the material or the gems cut from it. It is
simply
statement of fact and nothing else. I would sooner use well cut
quartz in my work that badly cut diamond. So whatever might be said
about the material itself, should have no bearing on the final
product.
I tend to agree with Andrew as to the interest factor in the silky
aquas. When in cab form they are very pleasing. I will pick them up
whenever I come across them. For me the rings I do with them sell
much better then the clear aquas.
I’m surprised nobody has mentioned that Aqua will occasionally ‘star’
or ‘eye’ and of course needs the ‘silk’ in order to do so. The
‘star/eye’ is brighter than Quartz ‘star/eyes’ but I’ve never seen
one that was very distinct.