ISG Diamonds Course: Lesson 14
Lab Created Diamonds
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We will begin our lesson on lab created diamonds with a simple review
of the synthesis processes that create these diamonds. What you may
find rather interesting is that while it took many decades to create a
process that would produce the first gem quality lab created diamond,
there are now two different main methods to create diamonds with
several sub-categories of methodology possible within each of the main
two.
The complete science of lab created diamonds are outside the scope of
this course, but given the speed at which the science of creating
diamonds is advancing this will be a topic that should be of ongoing
study to you as a gemologist.
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HPHT
We will begin with HPHT. This is “high pressure and high temperature”
process that quite literally duplicates conditions some 150km deep
inside the earth where natural diamonds formed billions of years ago.
By creating the same high pressures and high temperatures that were
present where natural diamonds formed, it was found that the labs
could take virtually any carbon source and force that carbon to
crystallize into diamonds. One of the first substances used to create a
diamond was a peanut owing to the high carbon content.
The first lab created diamonds made using the HPHT process were
normally yellow in color, due to the process itself not being able to
produce a truly pure carbon based crystal due to atmospheric issues of
the process itself. The smallest percentage of impurities would cause
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the yellowish color, which is why the early lab created diamonds were
known for their off colors of yellow to greenish yellow, and medium to
strong fluorescence.
CVD
The second method to create diamonds in a lab involves the CVD
process, or chemical vapor deposit. This is an entirely new concept by
which an environment is created where a carbon rich vapor is
introduced into an environment with a diamond seed and the vapor will
quite literally deposit diamond crystal layers on the seed. In this method
the diamond growth is better controlled and is actually a faster process
to grow diamond crystals. Due to the far more economic growth factors
most of the gem quality diamond crystals found on the market are made
using the CVD method.
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Let’s take a look at some examples of both of these processes from the
ISG Reference Collection of diamonds.
Here at left you see a HPHT yellow
lab created diamond of .35 carat
which was what was available in the
mid 1990’s. The technology of lab
synthesis of diamond had not yet
advanced to the point of creating
anything but small colorless
diamonds. Most were of a yellow
color as seen at left from the ISG
Student Reference Collection. This was also obtained from Thomas
Chatham of Chatham Created Gems.
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Eventually, however, the problems with yellowish colors and other
factors were overcome and a truly gem quality, lab created diamond
could be produced.
At left you see one of the first gem
quality HPHT lab created diamonds
from Chatham Created Gems. This
was obtained by the ISG office long
before it was the ISG office when I
worked in the Caribbean. It is #81 of
the very first gem quality lab created
diamond crystals. It is about .23 carat
so it is small. But at the time it was
virtually impossible to create large,
colorless gem quality synthetic diamonds.
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Eventually the technology advanced
to the point of what you see at left.
These are two Gemesis Created
Diamonds from the CVD process
from our ISG Student Reference
Collection and are available for
viewing in the ISG office for ISG
Students. These diamonds weight approximately .50 carat each and are
of VS clarity and G color. Beautiful lab created diamonds of high quality
and affordable price. This is the future of the diamond markets.
There are two important facts about lab created diamonds that you
needs to be aware of:
1. They are going to become a MAJOR part of the diamond market in
the next few years, and
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2. They are virtually impossible for you or me, even with all of the
tools we have, to separate from natural diamonds.
Regarding #1, we may have far more of these already on the market
than we know. When one lab can find a parcel of over 600 lab created
diamonds submitted as natural, there is honestly no telling how many
lab created diamonds are out on the market right now that no one
knows about. That is the first problem.
For #2, the problem is compounded by the fact that since these are all
crystallized carbon, the lab created versions do not vary greatly from the
natural, as they do with rubies, sapphires, etc… For while the chemical
makeup of a lab ruby will vary to a verifiable degree that allows for
identification, the fact that lab created diamonds are pure carbon and
natural diamonds are pure carbon severely limits the ability to separate
these.
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This leaves us with a significant problem regarding consumer confidence
in the diamond market, both now and in the future. If we don’t know
how to separate the lab created diamonds from the natural then how
can we, as gemologists and appraisers, provide some level of confidence
to consumers regarding our ability to do our job? The answer is, we
cannot. Which on its face would sort of seem like Game, Set, and Match
right there as far as lab created diamonds.
Fortunately, there are some “tells” that will help us know when we need
more advanced testing. Part of this is resolved by the fact that
companies like Gemesis Created Diamonds laser inscribes their
diamonds as you will see shortly. And regardless of what some may tell
you in the industry, it’s just not that easy to remove a laser inscription
off of the girdle of a diamond. So the first “tell” is that Gemesis and
other companies are making a legitimate and good faith effort to protect
the integrity of the market by marking their products for proper
disclosure.
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But what about those that don’t? Well, in these cases there will not be
much you can do other than treat the diamond, both grading and
appraisal, as if its natural. One important effort you can make is to ask
questions. Question the dealer, question your customer, ask questions
when presented with a diamond that is suspected of being lab created.
Often times these are sold as something quite special and the person
you are dealing with will be happy to share the facts with you. In that
case, operate as if this is the condition of the diamond. After all, if the
stone tests for you as a natural diamond and your appraisal customer
tells you that it is lab created, there is nothing wrong with going forward
with that piece of information as fact in your evaluation.
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As production facilities expand and the knowledge of lab created diamond
making increases we should anticipate that lab created diamonds are going to
become more and more prevalent, even beyond where they may be today in
our worst case scenarios. Given the sheer weight of lab created rubies that can
be turned out now by the flame fusion method, it is reasonable to assume that
this kind of production capability will someday be available for the lab created
diamond industry. Of course when that happens the price of diamond will fall
dramatically due to the problem with separation of the natural from
created. But there again, it
should be considered
that the ability to identify
the created diamonds will
increase with production. No
one knows, but as a gemologist
and appraiser
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you must be aware of the many potential problems and issues that the
diamond markets face both now, and in the future.
As we discussed earlier, Gemesis Created Diamonds puts a registration
number on all of their diamonds for proper disclosure. In the case of
the diamond at left, they have also added the fact that this lab created
diamond was irradiated to create a pink color. This makes our jobs as
gemologists and appraisers much easier, and helps to reaffirm
consumer confidence in the gemology and appraisal professions.
Below you see two Gemesis Created Diamonds of blue and pink colors.
As you can see from the images, these diamonds are very clean, very
well cut and proportioned and very fine quality.
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One important identifier of the pink irradiated diamond is that it is
extremely fluorescent to long and short wave UV. The fluorescence of
lab created diamonds holds great potential for the development of a
grass roots level identification tool in the future. While this is not a
diagnostic feature today, the very strong reaction in short wave UV is
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sort of unusual for natural diamonds but often seen in the lab created
diamonds. Something you should keep in mind for future reference.
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The main issue is that you cannot be
expected, and should not expect
yourself, to be able to identify synthetic
diamonds at this point in time. The
technology is just not there, not on a
day in and day out basis. Individual
stones, individual cases…perhaps. But as
far as advertising the ability to separate
natural from lab created diamonds, it’s something that you should not
attempt.
Since Raman Spectroscopy has become such an important tool for the
modern gemology, we want to demonstrate for you an example of
where the Raman actually cannot help with the separation of lab
created and natural diamond.
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Below is a Raman scan of a natural diamond. Compare this to the lab
created diamonds below that were scanned in the ISG office in
preparation for this course development.
Natural Diamond
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Chatham Created Diamond
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Gemesis Created Diamond
As you can see, all of the Raman scans are identical. Natural diamond,
Chatham Created Gem and Gemesis Created Diamond. This
demonstrates how even advanced testing is unable to separate these
which makes the issue of great concern on the market.
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For now, you must go with the information you have at hand. If you have
concerns or questions about the validity of a diamond source you should send it
to a lab with the tools to identify and separate. These tools are very expensive
and only available to the very largest labs.
Lab created diamonds are indeed a part of the future of this industry, most likely
a very large part. It will require that all gemologists and appraisers be continually
on watch for new information and developments within the market in order to
deal with these diamonds.
Let’s test your knowledge with a Quick Quiz on the next page. Please note:
There are four possible answers to every question. You may have to scroll down
using the control on the right to view all possible answers.
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