028

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS

By Maria Mrozek, Senior Gemologist GSI

One of fascinating features which gemologists are observing in diamonds, both natural and laboratory grown, are inclusions.

Inclusions are imperfections within a diamond that are result of different events during formation of natural and lab grown diamonds.  While nothing could be done regarding presence of inclusions in natural diamonds, when it comes to laboratory grown ones, diamond manufacturers constantly aim for the highest quality of stones, but the same time trying to mimic nature.

The gemologist considersany optically detectable internal irregularity other than fractureas an inclusion.Knowledge of inclusion types is essential and plays an important role in gemstone identification.

In natural diamonds inclusions help to learn and understand more about diamond origin, formation, and formation processes. In laboratory grown diamonds it helps to identify growth methods.

Natural Diamonds

Natural diamonds crystallize in the earth’s mantle. Internal inclusions can become part of a diamond during its formation from distortion in the structure during growth. Clarity characteristics make every diamond unique. It is highly improbable that two diamonds would have the exact same inclusions in the same location. Inclusion can help distinguish lab grown diamonds from natural diamonds. For instance, inclusions such as knot, twinning wisps, diamond crystals, other minerals, naturals, and indented naturals are evidence of the stone being a natural diamond.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 16

Most included crystals are smaller diamond crystal, usually appear white or transparent (above), they might also be crystal of other minerals – such as garnet or peridot which appear colored (bellow).

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 17

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 18A knot is an included diamond crystal that extends to the surface.

 

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 19Cloud of pinpoints, needles and crystals.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 20

Twinning Wisp – A series of pinpoints, clouds or crystals that appear flat and ribbon-like and forms in a diamond’s twinned growth plane, associated with crystal distortion during growth (left).   

 Natural – a portion of the rough’s original surface or skin left on a polished diamond. Natural shows smooth, irregular growth marks. The trigons are a common growth mark (right).

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 21

Precise analysis of inclusions can open the unique diamonds history and treatments. Correct identification of natural to lab-grown diamonds is important for market value and maintaining consumer confidence.

It’s important to know that there is distinct difference between inclusions in natural diamonds and laboratory grown ones. However, we must remember that all purpose of diamond growing is to mimic what is happens in nature, and this applies to inclusions too. There is constant race to make laboratory grown diamonds closer to natural ones in every aspect.

Today there are two main methods of growth:High Pleasure High Temperature (HPHT) and Chemical Vapor Deposition (CVD).

HPHT(High Pressure High Temperature)

The diamonds grown by the HPHT method in the laboratory arecreated using a catalyst. The typical catalysts being used are iron, nickel, and cobalt; however the use of other metals is possible as well. After the entire process is completed, we can observe metal inclusions formed by “trapping” a certain amount of catalyst flux during the formation process. In reflected light theseinclusions appear white, gray, or black with a metallic luster, in transmitted light they are opaque. Inclusions can either appear isolated, or in small groups. Often these inclusions are parallel to the outer surface of the rough crystal,however they can also be boundaries between internal growth sectors. One interesting fact is that depending on the size of such inclusion and its location, the stone could possibly be picked up with a magnet when there is a presence of iron.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 22

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 23

The metallic flux inclusionspresent in HPHT lab grown diamonds occur in variety of shapes, including rods, irregular forms, and some are associated with feathers.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 24The dendritic cloud with small round metallic crystal (left)and  thin needles (right).

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 25Groups of black triangular growth characteristics.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 26

The triangular growth features and hair-like inclusions (left) and large metallic inclusion with a cloud of tiny pinpoints (right).

CVD(Chemical Vapor Deposition)

The diamonds grown by the CVD method are on a thin plate of single diamond substrate. This process occurs in a vacuum chamber filled with a mixture of gases; hydrogen and methane. These gases are activated by energy sources – typically a microwave. The released carbon atoms are deposited on a diamond’s substrate layer by layer.

CVD-grown synthetic diamonds do not have metallic inclusions. Rather, they often contain dark graphite, or other mineral inclusions that are a result of their unique growth process. Graphite inclusions appear different from metallic, in that they do not have a metallic luster.

Inclusions in CVD diamonds occur as small dark particles or crystals that are generally non-diamond carbon.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 27

Fracture with non-diamond carbon.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 28
Internal features in the CVD lab grown diamonds contain irregular black inclusions composed of non-diamond carbon.

INCLUSIONS: A DEEP LOOK INSIDE NATURAL AND LAB GROWN DIAMOND CHARACTERISTICS 29Clouds of small dark particles occur in CVD lab grown diamonds.

About the author

Paree Bhattacharya
Website | + posts
Previous PostGeological origin of Natural Diamonds Next PostHow She’s Managing: GSI President Debbie Azar’s interview with JCK

Leave a Replay

Your email address will not be published. Required fields are marked *

FAQ

Where is Gemological Science International (GSI) located?

GSI is headquartered in New York, NY. It has 13 laboratories on four continents and in a number of countries: the United States, India, Dubai, Israel, Belgium, Hong Kong, and Botswana. This makes GSI one of the largest independent gemological organizations in the world.

Is there a difference between grading reports issued by different GSI laboratories?

All GSI laboratories grade using the same methods and adhere to the same standards. Every laboratory is staffed with highly trained professionals who have years of grading experience and an extensive gemological background.

What does it mean when a sales associate tells me my diamond is “GSI Certified” or is accompanied by a “GSI Certificate”?

The phrases “GSI Certificate” and “GSI Certified” are industry shorthand for GSI grading or identification reports. What this means to you is that expert gemologists and trained professionals meticulously evaluated the item. When your diamond, jewelry or gemstone is accompanied by a GSI grading report, you can be completely confident in the accuracy and objectivity of the evaluation.

Where can I find “GSI Certified Diamonds”?

GSI diamond grading and identification reports can be found in jewelry stores worldwide and online. Insist on a GSI grading report when shopping for a diamond, jewelry or gemstone.

What do I do if I lose my GSI Diamond Report?

Every GSI grading report is available on our website. Please visit gemscience.net and go to “verify your report”. Enter your GSI report number and you’ll instantly have access to a digital copy of it. You can also email us through the website to request a copy.

What are the 4Cs

A beautiful diamond is one of nature’s most mesmerizing creations. But how do you objectively judge the quality of the gem? The 4Cs – Cut, Color, Clarity, and Carat Weight – are the universal standard for doing this.

Is there anything beyond the 4Cs?

The 4Cs are an essential and important description of a diamond’s characteristics. But there is a considerable amount of detailed information behind each “C” along with other qualities of a diamond that affect its beauty, such as fluorescence, light performance and more.

How much do you need to know? That’s up to you, but knowing the 4Cs is almost essential.

What does a GSI diamond grading report look like?

GSI offers a number of grading reports (often referred to as “GSI Certificates”). You can see samples of them by browsing the Grading Reports page on our website.

What does a GSI colored diamond grading report look like?

You can see samples grading reports by browsing the Grading Reports page on our website.

What does a GSI Colored stone report look like?

You can see samples of Colored stones reports by browsing Grading Reports page on our website.

How does a GSI grading report compare to other laboratories that issue grading reports?

It is our policy not to comment on other laboratories. However, know that GSI adheres to the highest ethical standards. We do this in a number of ways:

  • Rotating gemologists to our different labs
  • Continuously upgrading our proprietary grading software to ensure full compliance with international grading standards
  • Having our gemological research department constantly investigate new developments in the industry, which informs the grading process

What’s the difference between a “GSI Certificate” and a “GSI Diamond Grading Report”?

GSI issues a variety of grading and identification reports. Consumers and industry professionals often call these reports “GSI Certificates”.

Select your currency
USDUnited States (US) dollar
EUR Euro