The beauty of a diamond is in the eyes of the beholder! What seems beautiful to one buyer is not always attractive to another. However, if the prices and quality of diamonds were left determined by each individual buyer, then we would have a chaotic gem industry with different prices offered for different qualities of diamonds. It, therefore, makes sense that a standardized system of evaluating diamonds was set up.
Before the current diamond grading and certification labs, diamonds were graded by merchants mostly by their color. Each local merchant had its own grading system. Some used triple AAAs to show the excellent color grade, others used roman numbers. However, when it came to international trading, there was no perfect way to standardize this grading and therefore diamonds ended up having multiple grades of quality.
In 1931, the nonprofit Gemological Institute of America (GIA) was founded. It is dedicated to research and education in the field of gemology and the jewelry arts. GIA was responsible for creating the current 4Cs grading system of diamonds in 1953. These are Color, Clarity, Carat, and Cut. Almost all current diamond grading labs use this system to grade diamonds, albeit improvised to fit each lab’s criteria.
While each lab has its own reasons for why they use different criteria for grading diamonds, it is clear that not all of them offer the best grading system. Therefore, the grading certificate on the diamond determines its price to some extent. For instance, a diamond rated excellent by GIA will be priced higher than another diamond rated similarly by, say, IGI. And here’s why.
1. Gemological Institute of America (GIA)
As stated, GIA is a non-profit institution established to provide research and education in the field of gemology and jewelry arts. The GIA is the oldest diamond certification lab and was responsible for coming up with the current standard grading system of 4Cs accepted worldwide.
According to the GIA, diamonds are rated on 5 grades depending on their color, carat, clarity and cut grade. These are:
- Excellent
- Very good
- Good
- Fair
- Poor
The GIA uses specific proportion measurements to determine a diamond’s quality through its cut grade. There are four aspects to a diamond’s cut grade, and these include:
- The table
- Length/Width ratio
- Depth
- Girdle
According to the GIA, these aspects must match certain proportions for the diamond to have maximum brilliance, scintillation, and fire. This allows for different cut shapes to be graded accordingly and the proportions adjusted in order to give the diamond maximum brilliance. For instance, a round cut diamond will not have the same length to width ratio as an oval cut diamond.
The color of diamonds is given a scale of D-M by the GIA, with the upper letters depicting colorlessness and the latter letters depicting warm colors. This is done through their fool-proof examination where the diamond passes through at least 4 gemologists with each consequent gemologist having superior experience over the preceding one. This guarantees minimal human error although it does not eliminate it.
The clarity of the diamond is also graded by observing the diamond through 10X binoculars. If there are no inclusions visible, the diamond is rated FL meaning flawless. If the diamond has a lot of inclusions, the diamond is rated I3 meaning three times included. The clarity grading moves from FL to IF (internally flawless, VVS1 and VVS2 (very, very, slightly included), VS1 and VS2 (Very slightly included), SI1, SI2, SI3 (slightly included), to I1, I2, and I3 (included)
If the diamond achieves excellent grades in all the three aspects, cut, color, and clarity, it is rated excellent.
Pros of GIA
Being a nonprofit organization, GIA’s evaluations of diamonds’ quality are more objective than other labs. This is because their grading is not geared towards pleasing customers but ensuring accurate grading of diamonds.
GIA is the oldest diamond grading lab and therefore has a lot of experience in the sector, unlike other labs that came later.
Their grading system is meticulous and is done by highly qualified professionals through a multi-tiered system. There’s minimal room for human error.
The lab uses proportion measurements allowing for accurate grading criteria for different diamond sizes and shapes to minimize a one-size-fits-all kind of criteria.
Cons of GIA
However, critics of GIA argue that their system has a lot of room for error. For instance, it is argued that their proportion system allows for different diamonds of similar quality to be graded differently since the proportion measurements change with each diamond.
Another criticism of the GIA is that its grading system is a bit broad, assigning only five grades to diamonds and thereby clustering grades of different but similar quality in a singular group. These critics insist that the AGS grading system is therefore superior to GIA as it assigns very specific grades to each aspect of the diamond allowing it to be more accurate than GIA. For instance, a diamond rated excellent in GIA could be a bit lower when rated by the AGS system of 0,0,0, as discussed below.
Verdict
Gemological Institute of America remains the number one go-to diamond grading lab and should be used by most buyers to determine the quality of diamonds. However, expect diamonds graded by GIA to be a bit pricier.
2. American Gemology Society
The AGS was established in 1934 as a non-profit association of jewelry traders. It opened its diamond grading and certification labs, American Gem Society Laboratories (AGSL), in 1996. It can, therefore, be noted they’re relatively new in the grading industry of diamonds.
The AGSL uses the same GIA’s 4Cs in grading the quality of diamonds. They, however, use concise measurements for grading the cut grade of diamonds. This means that they do not believe in modeling the diamonds’ cut measurements to achieve maximum brilliance. This makes their grading system strict and more rigid. However, it also ensures that the diamond’s grade is consistent throughout its grading.
They use a 0-10 grading system where 0 means super excellent and 10 depicts extremely poor quality. Each aspect, that is the cut, color, and clarity is evaluated separately and assigned its grade separately. Therefore, a diamond is labeled using three different numbers, on the cut, color, and then clarity. A super excellent diamond would be rated 0,0,0.
Pros of AGS
Being a non-profit and owned by jewelry stakeholders, its grading system is more objective and tailored to the needs of the jewelry stakeholders. It evaluates the diamonds’ quality based on a set of attributes.
Its system of precise measurements ensures that diamonds are accurately graded with no exceptions allowing for consistency in its reports unlike in the GIA.
Cons of AGS
AGS has inconsistencies when it comes to clarity. Different diamonds of similar clarity get graded differently which means you could pay higher for a lower clarity grade as compared to the GIA clarity grade.
Verdict
AGS and GIA are both the best diamond grading labs. You can trust AGS for a more consistent grading system than GIA, especially for fancy cut diamonds. However, GIA beats AGS on clarity consistency.
3. International Gemological Institute (IGI)
The IGI is one of the most renowned diamond grading labs in the world. It’s the world’s largest independent gem certification and appraisal institute for diamonds. It was established in 1975. They have multiple labs across the world, which allows for subtle inconsistencies in their grading system. As such, expect their grading to be one grade lower than GIA or AGSL. However, they have stricter standards when it comes to color and clarity than GIA, so if you’re looking for more clarity and better color, consider the IGI certification. However, their cut grade is lower and IGI-certified diamonds have a price discount of 12% compared to GIA. However, their grading is improving and almost matching up to the standards of GIA.
Pros of IGI
Stricter standards when it comes to grading color and clarity.
Cons of IGI
Expect one grade inconsistency in overall grading when it comes to grading cut grade.
Verdict
Use GSI when shopping for higher color and clarity grade diamonds. Use GIA or AGS when shopping for higher cut grade diamonds.
4. European Gemological Laboratory (EGL)
The EGL used to be one of the leading diamond grading labs. It was established more than 30 years ago and is credited with introducing the I3 clarity grade of diamonds. However, in the recent past, EGL has shown inconsistencies in its grading system and buyers should be wary when buying EGL certified diamonds only.
Compared to GIA, expect two grade lower inconsistencies when it comes to the EGL grading system as they’re less strict than GIA. However, most of the diamonds graded by EGL up to the year 2000 are accurate and consistent with the GIA grading system.
Cons of EGL
Less strict with a two-grade inconsistency level compared to GIA. Should be used together with another grading lab.
Verdict
Avoid EGL only certified diamonds.
5. Gemological Science International
The GSI is a commercial lab established in recent years. They’re mostly focused on mass grading of diamonds for commercial sellers and large chain stores because of their speedy service. Consequently, their grading system is a loser than GIA or AGS. It is also difficult to ascertain their objectiveness as they do this for profit. As such, diamonds graded by GSI are usually cheaper than those graded by GIA as they have lower standards when it comes to grading the diamond. Also, the color grading system of GSI which starts from D-Z makes it extremely difficult to distinguish adjacent colors creating room for inconsistencies in grading color. Buying a GSI only certified diamond is, therefore, riskier and could put you at risk of paying more for less.
Pros of GSI
Offers grading discounts to vendors.
Speedy grading services.
Cons of GSI
Very loose grading.
Inconsistency especially in color grades.
Verdict
Not recommended for individual buyers.
6. HogeRaadvoorDiamant
HRD was formed in 1973 in Europe. It claims to be the world’s authority for diamond grading in the world. However, their grading system has shown incredible inconsistencies. That notwithstanding, their strict standards on color and clarity make their diamonds to be two grades above the GIA and AGS grades. This allows for their diamonds to be priced higher than equivalent diamonds graded by GIA. Just like AGS, each of the 4Cs, cut, color, carat, and clarity are graded separately from excellent to poor. Color is graded from D to Z with D being colorless and Z having a noticeable yellow or brown tint.
Due to the perceived strictness in color and clarity grading, HRD diamonds are priced higher than GIA without due merit. This allows companies using HRD certificates to earn more profit than necessary. When well graded, it is expected that the diamonds would be two grades lower than what they’re assigned. It is therefore wise for a buyer to do price comparisons before buying an HRD certified diamond.
Pros of HRD
Perceived strictness in grading making them unnecessarily more expensive.
Cons of HRD
Color and clarity grades could be falsely two grades higher compared to GIA making you pay more for less.
7. Professional Gem Sciences
The PGS is a small lab founded by Tom Tashey, inventor of the SI3 clarity grade. Tom used to work in the EGL-LA lab. The PGS grading system is strict and consistent with the AGS system. Apart from its small size and smaller market share, PGS has a good reputation when it comes to grading diamonds. However, to protect your interests, buyers are cautioned against relying on PGS certificates and rather, going with large labs like AGS and GIA for accurate grading.
Pros of PGS
Strict and Consistent with AGS and GIA.
Smaller in size and tailored with the individual buyer in mind.
Cons of PGS
Too small to ascertain its credibility.
Verdict
Stick to large diamond grading labs unless you can ascertain PGS’ credibility. However, their grading system is still as good as GIA and AGS.
Conclusion
While there are numerous diamond certification labs out there, it is important to only go with ones that show consistency in their grading system as well as have a proven track record in their grading system. Furthermore, you should understand that the type of grading certificate on your diamond largely determines its price. Diamonds certified by strict labs like GIA and AGSL will have a higher price. It is also worth noting that non-profit diamond certification labs are preferred as they give an objective eye to diamond grades than commercial labs who are out to make a profit and please their customers. As such, here’s the list of the best diamond certification labs in descending order.
- Gemological Institute of America
- American Gemology Society
- International Gemological Institute
- Gemological Science International
- HogeRaadvoorDiamant
- European Gemological Lab
- Professional Gem Sciences