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Lapis grading system?


#1

Hi,

From time to time I see a reference in an article to “grades” of
lapis, implying there is some sort of formal grading system. It’s
usually in a context that leads me to believe it’s more than the eBay
A-AA-AAA stuff. I imagine that lapis grades would describe color,
amount of calcite, etc., but after some searching I can’t find any
(reputable) references. I realize most minerals don’t have official
grades (and that lapis is technically just a rock), but just in case,
does anyone know of an official standard or even widely accepted
lapis grading system? Thanks!

TC


#2

To say that ‘lapis is just a rock’ is too outrageous. The best lapis
comes from a mine that has been producing for over 6000 years.
Cleopatra had it ground up for eye shadow. Check out to see what the
Egyptians did with it. It is the blue used to produce blue in
stained glass in those great medieval cathedrals. Just a rock indeed!
There is no grading system for lapis. When you hear of AAA, etc; it’s
just the seller talking. I can call myself a ‘master jeweler’. It
doesn’t mean I am; so it is with lapis.

KPK


#3

A lot of dealers using A, AA, AAA, but it simply a convenient point
of reference and could mean different things with different dealers.
The desirable quality is saturated, violet-blue, medium dark, very
little pyrite or none at all if possible. If you can find one which
is semitranslucent, it would be a real prize.

Leonid Surpin


#4

There is none.

Generally, though, you can infer a rough grading methodology if you
simply look at the material and spend some time comparing pricing
among dealers. Tucson is a great place to do this. The amount of
calcite present is important. The best has none, the worst has
plenty. South American material generally is characterized by lots of
calcite, which may be in big globs or as micro-crystals that give the
lapis a very grayish appearance (like denim). The presence of pyrite
is a matter of personal preference and does not affect pricing,
although many prefer a slight amount of it in the finished piece.
Darker, intense violetish blue is more costly and rarer than lighter
shades or brighter blues. In the rough, pieces without separation
planes are more valuable as they will yield larger finished pieces.
But there is no formalized grading system. Like much of the
ornamental stone world, experience and time will be a guide. And
there will always be some disagreement… The benchmark for fine
lapis has always been the darker, evenly colored material from the
Sar-e-Sang mine in Badakhshan Province, Afghanistan. This mine is the
oldest commercial entity on Earth, providing lapis for over 4,000
years. Egyptian pharaohs sent expeditions here to retrieve lapis.
Peruvian material is, for the most part, relegated to tiles and
coasters and inexpensive carvings due to the grayish coloration
caused by prominent calcite.

Wayne


#5

Thank you all for your replies. First let me rectify a mistake:
“Just a rock” was entirely a mineralogical reference, and not in any
way reflective of the great beauty and value of the lapis gemstone.
My apologies to any admirers of lapis (and I am one) if I seemed
disrespectful!

Thanks for confirming that there is no official standard, and that
color & calcite mostly determine value. At my annual visit to Tucson
last year I tried learn more about lapis, and instead become
overwhelmed. There were so many offerings, most of them of good
material, and in so many price factors–everything from
euros-per-kilo to cents-per-ounce–that I simply lost track of what
was a good value. (Next year I’m taking a small database
computer…) I had hoped a standard reference could give me a head
start; I’ll just work out my own for next time.

Out of curiosity, if a gemological organization were to make a
reference standard, who would it probably be? GIA? ICA? Is there a
reason some group hasn’t already published a standard, other than a
simple lack of resources?

Thank you!
Tim Casey


#6

Standards in gemstones have been the thorniest issue since the time
immemorial.

The well hidden truth, is that the system that exist now, even in
diamonds, is very artificial one.

In order to be able to trade, standards are required, so we created
them, but every gemstone is unique and 2 gemstones which could be
graded the same, could sell for remarkably different amounts. Grading
gemstones is akin to grading works of Art.

Can we say that work of Michelangelo was better than work of Da
Vinci or vise versa ?

The only true guide is one’s eye and one’s sense of beauty.


#7
The well hidden truth, is that the system that exist now, even in
diamonds, is very artificial one. In order to be able to trade,
standards are required, so we created them, but every gemstone is
unique and 2 gemstones which could be graded the same, could sell
for remarkably different amounts.

“Artificial: applicable to anything that is not the result of natural
process or conditions.” So the system that exists, because standards
are required, is artificial? As diamonds can be graded by color and
clarity in a scientific way. Clarity is judged on whether the
inclusion is eye visible, visible under 10 power magnification, or 60
power magnification. Color is graded using graded stones. I therefore
submit that grading on color and clarity is based on the natural
process and conditions by which diamonds were formed. A Gemologist is
using the natural color and clarity as the criteria to separate
diamonds. Color, flaws and inclusions are measurable. When I went to
G.I.A. I understood that the school produces Gemmologists that can
grade color and clarity within 10% or each other. What I understood
was that the variance was one color grade or one clarity up or down.
In the G.I.A. labs diamonds are checked by three people. The criteria
developed by G.I.A. used by a trained Gemologist produces consistent
reproducible results. The grading is used to compare color and
clarity of various diamonds that can be used to establish a dollar
value. Dollar value is determined not by grading, but by the
marketplace. I went to G.I.A. in 1977. Over the years, no one paid
much attention to the value of cutting, and one advantage of being a
G.I.A. trained Gemologist was that with a 10 power loupe I could pick
the diamonds that were cut better that other in the same parcel that
were all the same carat price. People have become more knowledgeable
and now there is a value for better cutting. If someone does not know
what they are doing, they could try selling two diamonds that are the
same clarity, color, and cutting for remarkably different prices, but
if I was the buyer, I would not find value for myself or my customer
by purchasing the higher priced diamond when there is not value
gainer by the higher price. There is no well hidden truth.

Richard Hart


#8

Everything you said is correct and accurate, but it is still an
artificial system from the point of use of diamond in the design.
Whether the stone is flawless D or VVS1 E, the artistic contribution
to the overall composition is the same.

Also transparency of diamond is not taken into account in GIA grading
system. By transparency I do not mean inclusions, it is what used to
called “water” Two stones which would grade the same on GIA system,
but one from South Africa mines and another from India (Golconda)
will sell for remarkably different sum. I know that example is
theoretical because Golconda diamonds are not available anymore, but
for illustration purpose, it is valid

Leonid Surpin


#9
Also transparency of diamond is not taken into account in GIA
grading system. By transparency I do not mean inclusions, it is
what used to called "water" Two stones which would grade the same
on GIA system, but one from South Africa mines and another from
India (Golconda) will sell for remarkably different sum. I know
that example is theoretical because Golconda diamonds are not
available anymore, but for illustration purpose, it is valid

What gemological test can separate diamonds by “water”. What will
distinguish whether a diamond is from Golconda or any other diamond
mine. I understood that there was transparent, translucent and
opaque,
and I never heard of separation by various degrees of transparency.
If
it is not taken into account by G.I.A., where else is information
available. If I run across a Golconda diamond, and I can get more
money for it, I would surely like to know how to take advantage of
that opportunity.

Richard Hart


#10

The transparency of the diamond can be understood as transparency of
the water.

If we fill a glass of water from pristine mountain stream and
compare it side by side with the glass of water from the tap, the
difference can be seen.

The will be on other material visible but 2 glasses will look
different.

In diamond it can be explained by how well the crystalline structure
was formed. We know that diamond crystallizes in the cubic system,
but in process of formation there could be slight defects in the
crystalline structure. These defects, not visible even under
relatively high magnification, will interfere this the passage of
light and render diamonds less transparent to a different degree in
different diamonds. If diamond comes from geological deposit which
formed slowly the crystal structure would be more approaching ideal
and therefore more transparent to light. Golconda mines were such a
slow formed geological deposit. It is not likely that one can
encounter Golconda diamond, but to judge “water” in general,
submerge diamonds in liquid with refractive index approaching
diamond’s and compare the degree of visibility. The one less visible
will be the one with higher transparency. Even distilled water can be
used, but of course with less accuracy.

There is a book. The title is Romance of The Golconda Diamonds or
something similar. I even think I saw it on GIA website bookstore. It
should provide more on the subject.

Leonid Surpin


#11

Lapis is one of the oldest stones known. It was undoubtedly the
"sapphiros" mentioned in the Bible. Most of it comes from one
location and trade routes have existed from that location into the
ancient Middle East dating back 1500BC and further. There are a
couple of approaches to grading Lapis. Take a look at my book I have
an entire chapter devoted to connoisseurship in Lapis Lazuli.

Richard
Secrets Of The Gem Trade


#12

Pyrite is diagnostic of lapis: if it’s not there, it’s not natural
lapis. The pyrite may be be so fine that it’s not readily seen. The
desirable quality is determined by the buyer.

KPK


#13

Kevin,

I’m sorry, but your statement about the absence of pyrite being
diagnostic of simulated or synthetic laps is mineralogically
incorrect. Both Chilean and Afghani lapis is often found devoid of
any sulfide content whatsoever. Some material is almost pure
lazulite or, rarely, afghanite, but, being a rock (not a mineral),
there are a half-dozen other minerals that are usually present as
well. They might include pyrite, hauynite, sodalite, geyerite,
calcite, mica, and a number of other feldspathic minerals, etc., but
pyrite need not be present. One of the chemical clues to the
identification of pyrite is the release of hydrogen sulfide gas when
hydrochloric acid is applied, but that can be due to the presence of
pyrite or simply sulfur in the lazurite or longillite, when present.

Much of the calcite-rich Chilean material has no calcite whatsoever.

Wayne Emery