Was: Lapis grading system?
I never heard of separation by various degrees of transparency.
I have just finished reading R. Wise's 'Secrets of the Gem Trade'
and in that book, he refers often to the 'crystal' of a stone as
being important to it's overall uniqueness.
This is a quality in transparent gemstones that I have come across
from time to time.
It is difficult to define in a single stone alone, unless one is
very familiar with that type of material. However, when a stone with
crystal (or first water) is put next to an identical stone without
those qualities, there is a noticeable difference.
In my earlier career as a gemcutter, I cut well over 4000 cubic
zirconias, to use a familiar example.
And without a doubt, although the material came from the same
supplier, was the same colour and looked the same in the rough, a few
pieces of that rough simply produced better looking stones than the
others. Visibly better.
To give a recent example:
I cut two aquamarine coloured stepcut tourmalines from a single
piece of rough recently. I had to saw the original crystal in half,
because it had a fracture in the middle of the rough. ( luckily in
the middle) I cut two matching stones. The first gem was markedly
better than the second gemstone. Same angles, sizes, cutting and
polishing laps, machine and clarity, colour, flawlessness etc.
Yet one just looked better than the other.
The one has crystal--- that water clear look. The other is as clear,
as pretty, but simply comes second when you put the two next to each
other. I have not the faintest idea why, but I do know what I see. I
will also add that this 'quality' is not common. Going back on my
records, I have only two stones in the last 140 that I have cut that
I could say has the 'crystal' quality.
I assume this quality must be the same for Golconda diamonds, even
though I have never seen one.
Regards, Hans Meevis