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Diamond grading

Our 6 C in Diamond Grading explained

Carat - Colour- Clarity- CutCause- Certificate
 Noemi Diamonds 6C of diamond grading and the role of diamond origin
What makes the price of your diamond? 
First of all, the 4C, known as Carat, Colour, Cut, and Clarity. But now, also two more C's.
The 5th C: Cause, and the 6th C: Certificate will secure the long-term value of your diamond.


Conflict- free is not good enough anymore, active social engagement (cause) is better.


Conflict-free diamonds have a long history. The diamond trade established the KP (Kimberley Process) to eliminate conflict diamonds, and to certify diamonds as "conflict-free". Conflict regions come and go; some areas develop peacefully over time. However tight or not the KP control might be, continuous monitoring needs still need to be in effect at each stage of the value chain. Despite the process, things did not go always smoothly for the Kimberley Process. Unfortunately, it could happen that blood diamonds were certified by the Kimberley Process.  

The Kimberley Process comprises 85 countries, including multiple trading blocs like the EU. It is good to know that Russia is a prominent active member of the KP and therefore has voting rights regarding the definition of "conflict-free." The Kimberley Process is not independent of geopolitics. 

As the meaning of the term conflict-free is subject to controversy, the "cause" should replace the primary consideration regarding a diamond purchase. Hence, certificate issuers like GIA indicate the origin of the rough diamond. Buyers can choose between sources. Diamond miners are not all the same way ethically motivated. But some diamond miners are taking responsible action on ESG matters (see more information on our sustainable diamond page).

Causes mining companies can work on:

  • (Higher) education for disadvantaged people.
  • Empowerment of minorities.
  • Advanced healthcare, pregnancy protection, and childcare.
  • Providing work in deserted and remote regions, with otherwise bleak economic outlooks.
  • Fair wages. 
  • Insurances and retirement plans. 
  • Access for workers to resources like clean water and other supplies. 
  • Financial literacy and access to banking. 
  • Access to micro financing. 
  • Improvement of digital skills and global connectivity.

But also gender equality and diversity, as well as sustainable and safe housing, and community buildings. 

It is essential that diamond mines publish standardized ESG reports so the public can better understand what kind of measures they are taking, and how sweeping they are. 


What impact will the origin certificates have on the price of diamonds?

As more consumers join the movement, the value of diamonds from not ethically operating diamond mines is at risk. In addition, if more consumers request certificates of origin, diamonds of undesirable provenance will be more challenging to sell. 


How do we know about the origin of diamonds?


The leading diamond- lab GIA now offers an origin- report. That means that the consumer can trace the diamond down to the mine. Diamond traders recommend controlled mining. Controlled mining implies that a mining company has funds to invest in environmental and social efforts to improve actions for more sustainability and better social care.

There are also uncontrolled sources, such as South America's alluvial collections or family-run enterprises. They are more challenging to monitor and less stabilized than the big mining companies. For example, alluvial mining (organized an unorganized collection of diamonds washed at shores and rivers) tends to disregard the property rights of existing landowners like indigenous people.

The countries' laws also play a significant role in environmental protection. For example, Angola has widely prioritized mining over nature, with disastrous consequences for the landscapes and biospheres. On the other end of the scale, Canada is implementing adequate legislation.


Responsible trademarks 

  • Canadamark (TM) 
  • Argyle (TM).
  • GIA Diamond origin report (TM). 
  • The Rapaport Diamond Certficate (TM)


Blockchain provides evidence of origin. 


Natural diamond producers have founded a project called Tracr TM to follow the diamond to its origin by blockchain. The blockchain company Everledger supports various blockchain projects in the diamond industry. Their blockchain sits on Ethereum 3.0. Ethereum 3.0 has used its new technology, "POS," since September 2022, which consumes significantly lower energy (-99.7%), according to Ether. 

Blockchain can prove the journey of a diamond accurately, but not yet seamlessly. That is because a rough diamond is a physical object that will be moved, altered, reduced, and fragmented before it enters a new life as one or more freshly cut and polished diamond(s). There are still technical challenges. However, blockchain helps the industry to become more transparent which is very positive. 

Some mining companies like De Beers are making progress in integrating blockchain technology. About 25% of the de Beers production is blockchain verified. The system's success will likely depend on whether blockchain will be 100% applicable in the future.  




Noemi Diamonds explains GIA diamond origin certificate

The 6th C: The Certificate

It secures the value of your diamond


The GIA origin report works with an independent audit firm to trace diamond origins and their journey through the value chain. The audit service is vetting cutters and verifying receipts and transactions to make the diamond's origin transparent. Consumers can verify the report number on the GIA website. 

Find more information here


Did you know? Professionals buy diamonds "on paper" only based on the grading report. So they don't necessarily need to look at the diamonds. 

It is sometimes inevitable to examine a stone with one's own eyes. But, in the case of a sealed stone with a GIA origin report, it is often unnecessary. 

The condition for this confidence is that the report is of a highly reputed gem lab. The international diamond trade tends to rely on the standards of three diamond-grading labs: GIA, HRD, and IGI. 

GIA (Gemological Institute of America) is the leading authority, offering the broadest service and investing in education and research. The best resell- value for the consumer comes from GIA reports, followed by HRD (an independent subsidiary of the Antwerp World Diamond Centre). IGI represents an acceptable grading standard and is now in the ownership of a Chinese group. It is the standard for lab grown diamonds. 

Other accepted grading standards are SSEF and Gübelin, two Swiss companies.

The Rapaport diamond certificate requires a GIA lab- report and is therefore a double grading (first by GIA and then by Rapaport). If you own an investment grade diamond now, it could be beneficial to perform an additional grading as investment diamond.

We recommend to renew the lab- reports from time to time to keep it up-to-date. 


Noemi Diamonds about the four C of diamond valuation


The 4 C's in one model

The graph shows the virtually pictured multi-layered "price engine" of a diamond. The four propellers C- Carat, Colour, Clarity, Cut turn each of them the price either to a higher or lower value. Their different quality antipodes drive the dynamic range of diamonds of commercial gem- quality. The lows and highs have a common range in jewelry. In Colour, the exceptionally high quality is the colour D, for the lower end it is J. For the Clarity it is from FL/IF- (Internally) Flawless (high quality) to SI (Slightly Included). For the Cut, it is from Ideal/ 3x Excellent (Triple Ex) to Good as a low but under the circumstances considerable quality. And the Carat size propels the diamond to a higher value or lesser value, too.

Did you know? For a 1 Carat Round Brilliant diamond, the lowest quality which a professional would probably advise would be a J Colour, Good Cut, SI2. At the other hand, the best quality customers can get like a 1 Carat would be an Ideal Cut/ Triple Ex, D-Colour, IF/ FL (Flawless) diamond. Consider both the diamonds would have a GIA certificate.  

The price difference for a 1 Carat of different qualities can be as high as 13000 Dollars and more. 


Hands-on: Carat, Colour, Clarity, Cut 


Imagine you want to choose a diamond for your engagement. You go to your favourite Jeweler and tell him: I am planning to give a diamond ring to my love. I saved a very long time to buy a beautiful engagement ring (or anniversary/ birthday ring). Now, my budget is 16.000 dollars. I want to get something exceptional and highly valuable for my money. Which diamond can you offer to me?
The Jeweler comes back with six diamonds. He says: They all cost the same. I ask 16.000 Dollars for each. They all have a GIA certificate, no fluorescence and a Triple Ex cut.

Which one is best for you?

  • 1.33 Carats, D, VS1
  • 1.4 Carats E, VS1
  • 1.42 Carats, F, VS1
  • 1.5 Carats G, VVS2
  • 1.5 Carats H, IF
  • 1.8 carats J, VVS2

Who didn't think at first sight the 1.8 Carat would be the best one? Now you might wonder: Which one should you choose and why? While looking at the diamonds, you start to doubt. Ok, you can see the difference in size, yes. The 1.8 Carat immediately attracts your attention. But does the slight variation in the colour matter? And will your love ever take a loupe to find that one tiny impurity which the certificate mentions and which the Jeweler says to be so-called "invisible with the naked eye" and "eye-clean"?
Does the Jeweler speak the truth when he is saying that this diamond of 1.8 Carats has the same value than the smaller one of 1.33 Carats?
The answer is, Yes, the Jeweler is right with his offer. All those diamonds- within the range mentioned in our example- trade more or less as the same value in money.The price of diamonds is daily/ weekly fixed at the diamond exchanges of the world. That means, that, in a commercial sense, none of the diamonds which the Jeweler selected for you is more precious than the other.
Is it then up to you, which Characteristics of the diamond you value most?

Please see the following information which has been written to help you make your choice. 


Does size matter? The answer might surprise you. While bigger diamonds are certainly showstoppers and will add visibly to your glamour, the average size for an engagement ring varies per city. According to a study, you needed in New York in 2019 a 1.45-carat engagement ring, while in LA, it was a 0.83- carat ring. Fashion and social expectations play a role and influence the reselling value of your diamond. The average German engagement- ring size in 2019 was 1.18 carat. Diamonds sizes, which are in the trend, sell faster and make your love happier. 

A diamond meeting investment grade criteria should have a weight of a minimum of half a carat or higher. 


Did you know that diamond graders need a special light to determine the exact colour grade? That should be either a particular lamp or the "cold" Northern daylight at noon with absolutely no ray of sunlight or colour reflections of the environment. Only by then you can tell the subtle differences!
There are many articles about diamond colours in general with a lot of information. But the variety of colours, including the lower end is overwhelming for the customer. Here is what you need to know:
The colours D- E/F fetch high prices. They are pure exceptionally white and are eligible for "investment-grade" diamonds, which means that the trade is quite sure about the future evaluation of the diamonds with this particular colour range. According to what we know by now, your D-E diamond will always be in demand, because it is so rare. Even Jewelers might have the challenge to find yours in the size you want. Of all diamonds mined, only a tiny fraction of gem-quality diamonds are of the exceptional white colour.
F as a "Rare white" colour grade is beautiful to have, too. There are not so many diamonds on the world of this shade- they appear only from time to time. But that diamond ring of your best friend might be a G-H colour. It seems to be "White". Will you see the difference?
Think about it: how often are you outside with your diamond in "Cold Northern Daylight" and have a diamond connoisseur looking at your jewel (given that there are no reflections of colourful objects in the environment)? -

Right. In all other cases, your G-H diamond will sparkle white, just as beautiful as the D- F qualities. However, it is essential if you choose this appealing colour range not to trouble the impression. Flaws in cut or too many impurities can manifold the hint of warm white. G-H Colours have the best effect with high clarity and a perfect cut, which should also secure their desirability in the future.
D- G colour diamonds are recommended to be set in white gold or platinum settings. The reflections of the tinted gold would otherwise influence the white appeal of the diamond. Notabene, this is only the case for the tiny setting around the diamond itself. The necklace, bracelet or ring body can be of Yellow or Rose Gold, too.
The colour J is at the lower end of the usual diamond colour range which Jewelers offer. But, it is Slightly Tinted White. Therefore, they trade significantly lower in price although their brightness is appreciated, too. Sometimes, you see the colour J with its somewhat visible "Warm White" combined with impressive high carat sizes. This kind of offer is desirable for diamond lovers who prefer big sizes or for those who want to set the diamond in yellow gold settings. In terms of investment, the long-term value of J- Colours is not as natural to determine as the ones of Exceptionally White- White colours. There are more insecurities concerning the future demand for this colour. However, the striking impression of a relatively big J-colour diamond might create the moment of surprise and happiness you want.

Investment grade diamonds are required to have a colour grade D-H. 



While the colour of a diamond might appear for some buyers the most apparent attribute, the clarity decides on the value, too. A flawless diamond has neither inside nor at the outer skin a flaw. An internally flawless diamond (IF) has just as little effects inside but could have minor details of polish at the outer surface. In the VVS grade (very very small inclusions), the tiny imperfections are invisible with the naked eye. It would be best if you had a 10x loupe to discover them. And an experienced diamond professional will have to look at the certificate which maps the exact location of the blemishes; otherwise, they will be challenging to find. Microscopic inclusions (VS clarity grade) can hardly become visible in the eye-sight: the stone is so-called eye-clean. In clarity grades from SI1 onwards, you can see the inclusions very often without the loupe. Also, they start to disturb the perfect brilliance of the stone because they interfere with the geometrical order of the cut. (SI2) is already a questionable clarity grade. In (I) included grade categories, the inclusions are so visible that most people will start to see them even from a distance. Therefore, diamonds with a clarity grade (I) often do not reach the shops of the jewelers. The usual range is between (IF) and (SI1). Fancy colour diamonds do not always have a clarity grading, as their colour intensity is the most desirable part of the characteristics.

Investment grade diamonds are mandatory to have a VS clarity grade or better.


When it comes to diamonds, cut is one of the most important factors to consider. A diamond's cut refers to how well the stone has been crafted and how well it reflects light. A well-cut diamond will sparkle and shine, while a poorly cut diamond will look dull and lifeless. So, what exactly makes a diamond cut great, and why is it so important?

  1. Reflection of Light: A well-cut diamond will reflect light beautifully, creating a brilliant and sparkling appearance. The light enters the diamond through the table (the flat surface on top) and is then reflected back through the pavilion (the lower section). If the cut is too shallow or too deep, the light will escape out the sides or bottom of the diamond, resulting in a less sparkling appearance.
  2. Proportion: The proportion of a diamond refers to how well the different parts of the stone are balanced and harmonized. A well-proportioned diamond will have a balanced table, girdle (the thin band around the middle of the stone), and pavilion. A poorly proportioned diamond will have an unbalanced appearance and will not reflect light as well.
  3. Symmetry: The symmetry of a diamond refers to how well the different parts of the stone are aligned. A well-symmetrical diamond will have all its angles and lines perfectly aligned, while a poorly symmetrical diamond will have visible asymmetry and will not reflect light as effectively.
  4. Brightness: Brightness refers to the amount of white light that is reflected from the diamond. A well-cut diamond will reflect more white light, creating a bright and sparkling appearance. A poorly cut diamond will reflect less white light and will look dull and lifeless.
  5. Fire: Fire refers to the amount of rainbow-colored light that is reflected from the diamond. A well-cut diamond will reflect rainbow-colored light, creating a dazzling and colorful appearance. A poorly cut diamond will reflect less rainbow-colored light and will look less dazzling and colorful.

In conclusion, the cut of a diamond is an important factor to consider when buying a diamond. A well-cut diamond will be beautiful, sparkling, and full of life, while a poorly cut diamond will be dull, lifeless, and unimpressive. So, make sure to choose a diamond that has a great cut, and enjoy all the beauty and brilliance that a well-cut diamond has to offer!