Before you buy that pricey engagement ring, necklace or bracelet, you may want to ensure that its quality is verified. This verification needs to be done in an objective 3rd party laboratory which describes the diamond based on its primary characteristics. This means you will receive a lab certificate or report describing what is known as the 4 Cs of diamond grading, i.e. clarity, cut, color and carat, as well as other relevant characteristics.
There’re various certifications and standards developed to evaluate the quality and characteristics of a diamond, but the most important one is the GIA certification.
What is GIA Certification?
In the diamond business, the most important diamond grading laboratory is GIA (Gemological Institute of America). The GIA labs invented most of the systems used in grading diamonds today, including the 4 C’s of diamonds. The labs are completely unbiased in their grading, which is why they are the most trusted and widely respected source for buyers and entrepreneurs who want to know the true diamond's quality.
Entrepreneurs trading in the diamond business usually submit their pieces to GIA labs for analysis and evaluation in order to receive a certificate that enumerates all the important characteristics of that particular piece of diamond. So in addition to the 4 C’s of diamonds listed earlier, a GIA lab will also evaluate many other things including the table %, depth %, culet size, symmetry, proportion diagram, girdle thickness, polish grade, laser inscription (where applicable) and security features.
The GIA lab has no financial stake in the sale of a diamond, which is why their evaluation is the most rigorous and most subjective. Due to the reputation, proven consistency and history of trust, most experts and traders recommend buying diamonds that have a GIA certificate.
There are several reasons why a certification matters in diamond trading. The most important reason is price determination. Diamonds are priced based on their quality. For instance, the difference in pricing between an SI2 clarity and an SI1 clarity can be significant. A GIA certificate essentially makes the comments and opinions of the person selling the diamond less relevant. The qualities of the diamond outlined on the certificate belong to that particular piece of diamond, and it doesn’t matter what the seller has to say.
A closer look at the GIA lab
As earlier mentioned, GIA is the most trusted, leading gemological laboratory in the world. The GIA is a non-profit institute headquartered in Carlsbad, California and has offices in 13 countries, employing over 1400 scientists, certified diamond graders, and educators. The institute is dedicated to education and research in the field of jewelry arts and gemology.
GIA was founded in 1931 with the primary mission of protecting all sellers and buyers of a gemstone by establishing and maintaining the standard analyzing the quality and characteristics of the gemstone. The Institute achieves this through gem identification, research and diamond grading services, in addition, a wide range of other education programs. The Institute acts as a source of jewelry and gem information center for traders, media outlets, and the public.
The GIA Laboratories provide a number of gem identification and grading reports. More specifically, diamond grading reports provide information on clarity, cut, color, and carat weight. GIA labs issue two types of reports i.e. the Diamond Grading Report, which is more detailed and the Diamond Dossier, a less expensive and briefer version.
The Diamond Grading Reports contain a number of measurements, (discussed more in the next section) and also the type and location of other inclusions in the diamond. Today, Diamond Grading Reports are demanded by a majority of buyers purchasing more than a certain size, typically 100 mg. Buyers purchasing over 200 mg will almost always demand a certificate as it’s considered a critical tool in guaranteeing the accuracy and quality of the diamond as represented to potential buyers.
The GIA report may include comments about any treatments detected and country of origin for sapphire, ruby, tourmaline, and emerald. Pearl reports will specify the size, weight, color, shape, presence of treatments and origin (cultured or natural).
GIA Diamond certificate/Report
GIA has an International Diamond Grading System that includes the 4 C’s we talked about earlier. The 4 C’s of diamond as we know them today were developed by the GIA. The Gem Trade Laboratory Report for diamonds, commonly referred to as GIA certificate is currently the world’s most accurate, reliable, valuable, and recognizable diamond grading report.
The report provides extensive details about the diamond and also offers a diagram of external and internal characteristics or flaws. Think of it as a fingerprint that uniquely identifies a particular diamond and can be used to verify it later. The G.I.A. only grades natural diamonds, so if you’re purchasing diamonds that have a G.I.A certificate you can be assured that the diamond is not synthetic or clarity enhanced.
The GIA also analyses the diamonds to produce a GTL report using the Sarin Diamond Proportion Analyzer. However, this information is currently not disclosed by in the GTL Report, but it’s retained as additional identification info on that specific diamond. If you’re after ideal cut diamonds and would like to know the pavilion angles, crown angles, and other proportional details, you will have to request your vendor for the Sarin Diamond Proportion Report. Any vendor serious about offering ideal cut diamonds should have this report.
If you’re interested in the Sarin Diamond Proportion Report, you should not be enticed by your vendor to accept a report from another lab in place of the GIA report. You should rather stick with the GIA Report for gemological accuracy and then request for an additional Sarin Diamond Proportion Report. This will ensure that you never get the wrong clarity, color, polish, clarity, cut, fluorescence and symmetry rating. Let’s break down the contents of a GIA report.
The anatomy of the GIA diamond report.
The 4 C’s are the meat and potatoes of the GIA Diamond certificate/Report. Let’s take a look at each of them in detail.
This is the first of the diamond’s 4 C’s. Color will appear directly under your results header on the report, and it’s often rated on a scale from D-to-Z. The alphabetical scale essentially measures the absence of color. So a diamond rated D, for instance, means it’s colorless –which is a desirable characteristic. On the flip side, a diamond rated z means it’s either brown or yellow-tinged, which in essence reduces its value.
The comments and descriptions that go along each individual letter rating are: colorless, near colorless, faint, very light, and light. You might also notice a color rating letter with an asterisk next to it, this means the stone might have been treated to enhance its natural color. If there is a fancy diamond color and if treatments were done specifically for that, it will be detailed in the GIA Colored Diamond Grading Report.
II. Carat Weight
Carat weight is another C that is closely related to the price of the diamond. This is quite logical in the sense that the heavier the diamond, the larger it is, and as you might already know, large diamonds are very rare. The GIA measurements on your report will be represented to the nearest hundredth of a carat – one carat is equal to 1/5 of a gram.
A diamond’s clarity is a little more difficult to evaluate than its weight or color and requires sophisticated equipment coupled with professional training. The primary purpose of determining clarity is to reveal all the inclusions in the interior or surface blemishes and stains. As you would expect, the lesser the blemishes and inclusions are, the more expensive the diamond is.
In the GIA report, characteristics of clarity are represented on a plotted diagram. In the GIA Diamond Dossier report, the characteristics of clarity will appear listed. The listing of these characteristics will appear in order of their severity based on the size and position of the inclusions. Generally, the diamond’s clarity will be rated as Internally Flawless, Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2 – (Slightly Included), or I1, I2 or I3 – (included)
The last C is attributed to the human’s effort of enhancing the beauty of the diamond through cutting and shaping. The GIA sets the cut grade of a diamond determining the dominating shape of the stone and calculating the proportions of the facets that influence the appearance of the stone. Classification of the cut quality is rated as Excellent, Very Good, Good, fair or poor and is influenced by factors such as symmetry, polish, durability, weight, and scintillation.
This measurement is usually accompanied by diagrams showing the diamond’s profile.
Other measurements and details in the GIA report.
In addition to the 4 C’s, the GIA diamond report also details other characteristics that reveal more about the diamond in question. One of the most noticeable additional details is the fluorescence, which is the ability of a diamond stone to emit a certain glow when exposed to a UV light. Only a small percentage of diamonds can exhibit fluorescence. The scale of diamond fluorescence runs from none through faint, medium, strong, and very strong. The measurements of the diamond are determined using complex equipment while the shape is determined using the grade analysis. There is also additional grading information about symmetry and polish of the stone in the report. Polish is essentially how smooth the diamond surface is while symmetry represents the alignment of the diamond’s outline, facets, shape, and placement. Symmetry and polish are graded ranging from Poor to Excellent. Other details here might include the depth percentage, girdle, culet, and laser inscriptions.
The report also has a comments section which may include notes on other attributes that might have been observed during the evaluation. Details here might cover things like the possible origin of the diamond, detected treatment used to enhance color and clarity, unique blemishes or any other useful information.
Other Certification Labs
As earlier mentioned, there are other certifications developed by a number of different labs like the AGS, EGL, and IGI. Let’s take a quick look at each of these.
The American Gemological Society (AGS) is also a US-based lab headquartered in Las Vegas. The AGS lab is well known for their scientific approach and diamond grading system research. Instead of an alphabetical scale, the AGS system uses a scale of numbers from 0-10 for rating the characteristics of diamonds, with 10 as the worst and 0 as the best.
The European Gemological Laboratory (EGL) is a European based grading agency with a solid international presence. The agency has offices in Paris, London, Tokyo, Tel Aviv, Johannesburg, among other major cities. They are renowned for developing diamond grading technologies and techniques for stones that weigh less than a carat. They are also known to have introduced an additional SI3’ diamond clarity rating.
Lastly, the International Gemological Institute (IGI) is headquartered in Antwerp, Belgium. They are the second best known and most popular diamond graders after the GIA. A good number of diamonds in the market carry the IGI certificate and are popular in the Asian countries. They work pretty firs, and their prices are cheaper than those of GIA, but this doesn’t necessarily appeal to the end consumer.
The EGL and IGI are more popular and widely known outside the US, especially in Asia and Europe, but they both have offices and operate in major American cities like Los Angeles and New York. So you will commonly see retailers selling diamonds accompanied by reports from this labs. However, most industry experts don’t recommend them due to a history of inconsistencies and inflated quality claims.
Diamond certification is a very important aspect that assures the buyer that the qualities of the stone claimed by the seller are legit. A diamond has to be taken to a lab for the quality and characteristics of the stone to be evaluated. The most valuable, reputable, trusted and widely accepted diamond certification is the GIA certification. The GIA diamond grading system evaluates and analyzes important characteristics such as the 4 Cs (cut, color, clarity, and carat weight) as well as polish and symmetry. While there are other certification labs such as AGS, EGL, and IGI, it’s always recommended to insist on the GIA report as is the most standardized and trusted diamond certification.