Diamond Certification: Buying Guide On How To Buy Diamonds For The Right Price

Looking to purchase diamonds but don’t know where to start? Want to make sure you get the right price?
diamond certification

Baseline Recommendations

You get the evaluation of diamonds and the relevant certificates from independent grading labs that conduct tests.

There are no real guidelines to the grading process that labs follow.

This means labs create their own processes and procedures over time.

Some labs do this at high standards and some not.

It’s important to know this!

Make sure you pay an appropriate price for the type of diamond you’re getting.

When you purchase your diamond, we recommend you use diamond certificates from GIA and AGS labs.

There’s proof that they are the most consistent labs in the grading process.

We want you to make the best decision.

A diamond is an important purchase, right?

If you’re anxious about the documentation you receive, talk to us.

Or perhaps you have questions about the purchase process.

We’re here to assist!

Understanding Diamond Certification

A certificate, also known as a Diamond Certification, is what you’ll get from a lab.

It details information about a diamond and all its traits.

These lab entities are generally 3rd party labs.

Examples are GIA, AGS, IGO, EGL, GSI and HRD.

Each diamond you’re able up for sale goes through an evaluation process to understand its traits.

Along with your purchase, make sure you get this certificate that explains these details.

There are many traits but common ones are the diamond’s dimensions, color and clarity.

Trained professionals use specialized tools in the process to confirm all these details.

Different lab entities evaluate, grade and characterize diamonds differently.

They may yield very different outcomes from each other.

Therefore, it’s important to find out which lab holds a high level of integrity and has reliable processes.

With different labs yielding different results, note that prices and values of the same or similar diamonds will differ.

When you purchase your diamond, use an industry respected lab and evaluators.

Also check the diamond yourself before paying for it.

Do you need to buy a diamond and would like an expert to look through its certification? Then get in touch with us.

Diamond Ring Certification Guidelines

Consistency Is Key

Consistency is the key that will give you peace about the lab you choose to use.

As mentioned, different labs will grade a similar or the same diamond differently.

So, it’s important that the lab you use for certification offers consistency around its grading.

When comparing labs, one entity isn’t necessarily better than the other for giving a certain rating.

If one reputable lab provides a different grading than another center on a regular basis, that consistency is valuable.

An example is to use the color grade.

The same diamond can be graded this way:

  • H with an IGI certificate

  • I grade using the GIA certification

With this example we see that the IGI certificate is simply weaker than the GIA certificate.

Instead of basing your decisions on the certifications’ different grades, it’s best to base your decisions on the grading lab’s consistency.

Diamond Grading Is Not Always Objective

Diamond grading isn’t governed by a specific body and specific guidelines.

However as stated, consistency is key and how you build trust in a lab.

If the lab consistently grades a certain color ‘G’ and another lab ‘H’, this is acceptable.

As long as it’s consistent.

With all this said, note that if a lab is consistent in their grading, it doesn’t mean you can always trust them.

You may still end up with a weak grading certificate.

This leads to you spending more on the diamond than is actually worth.

Price vs Certification

Besides all of that, the final price of a diamond is an important factor to consider, irrespective of the certification.

The cost of a diamond reflects its characteristics – the quality and cut.

If you’re hesitant about the asking price of a diamond, take your time to get a second opinion.

Get the help you need to make the final purchasing decision.

Should you have these queries before a purchase, get in touch with us.

Laboratories can Provide Different Outcomes

Also, different labs favor different aspects of the grading process.

Some will grade color as the most important aspect of a diamond while other labs prefer clarity.

And some labs favor an array of factors.

Because of this, diamond companies learn which grading labs to send their diamonds to.

They want to get the right evaluations and true worth of their diamonds reflected on certificates.

This also ensures the diamonds you eventually buy are worth what the report grading represents.

Should you still need more clarity and information about certification labs, get in touch with us.

The Top Diamond Certifications

There are two entities in the diamond certification industry that people call ‘the best’.

These two entities are GIA (Gemological Institute of America) and AGS (American Gem Society) and they’re the most consistent grading labs.

Trust is well deserved, especially around the grading aspects of color, clarity and cut quality.

These labs are more thorough in their grading work when compared to the rest.

Reports and certificates from them are trustworthy.

We recommend purchasing diamonds with certification from them.

1. Gemological Institute of America Certification

The Gemological Institute of America (GIA) is an organization well known for its diamond grading skills.

The company is reliable and they provide accurate data that gives you reassurance when purchasing diamonds.

GIA is a nonprofit lab so they don’t make money on diamond sales.

They simply provide various evaluations on the quality of a diamond such as the following:

  • Diamond shape

  • Cut of the diamond

  • Diamond’s date of evaluation

  • Measurements done in millimetres

  • Table percentage

  • Carat weight

  • Depth percentage

  • Symmetry of the diamond

  • Culet size

  • Polish grade

  • Proportion of the diamond

  • Cut grade of Excellent, Very Good, Good and Poor

  • Clarity grades such as IF, VVS1, VVS2, VS1, VS2, SI1 and SI2

  • Blemishes

  • Diamond inclusions

  • Girdle thickness

  • Security aspects

  • Fluorescence grade

  • Laser writing

  • Any comments on diamond features

GIA is thorough when it comes to grading diamond clarity and color.

We advise that you only purchase stones with a GIA or AGS certificate because of their accuracy and reputation in the industry.

2. American Gem Society Certification

The American Gem Society (AGS) boasts being the first to give exact grading on diamond cuts.

Before GIA established its stone cut rating AGS introduced its own innovative diamond cut grade scale.

This scale is between 0 (known as ideal) and 9.

AGS had control over the ideal cut marketplace a few years back.

They worked with reputable shops.

Back then, the diamond would only have the ideal cut rating from the American Gem Society.

Since the GIA started offering diamond cut grades, the AGS share in the market reduced drastically.

The AGS attempts to establish themselves as being classier than the GIA with their grading certification.

But there are rarely any differences based on accuracy and reputation that separate these laboratories.

However, the American Gem Society is still the preferred laboratory.

This is because of its cut grading certification on perfectly cut round diamonds.

Furthermore, upgrade shopping is another aspect you must be aware of.

Laboratories aren’t precise on clarity and color.

This is because these grades aren’t as easy to pinpoint like diamond weight and dimensions.

A retailer will send a diamond to various laboratories to get a higher grading if it’s in between ratings.

For example, a diamond between a weak I and a strong J color may get a J rating from GIA.

However, the vendor may send it to the AGS to get the I grade.

This is so the retailer can sell the stone at a higher price.

It’s expected that the grading will be identical but it’s typical the vendor will get an upgrade.

The upgrade will make the money back that was spent on the AGS certification.

It’s common for vendors to use the AGS for branded ideal diamonds including Hearts on Fire and True Hearts.

But they aren’t regularly used for non-round diamonds.

For example, imagine 59 out of 60 cushion cut stones are certified by GIA and one is rated by AGS.

That one may have been upgraded.

This is by no means the AGS’ fault.

We’re simply giving you information about how some sellers may try to cheat you into buying lower grade diamonds.

Of course it will be at a higher price than necessary.

Furthermore, the AGS is an incredibly reliable group.

That’s why it’s important to only accept certification from the AGS and GIA.

Contact us if you want more information about AGS certification. We’d be happy to assist you.

3. International Gemological Institute Certification

The International Gemological Institute (IGI) started as a manual stronghold in the diamond trade.

This institute was the most popular diamond laboratory for many jewelers in Canada and the USA.

IGI works quickly and their grading prices are more affordable than GIA. GIA’s ratings may appeal to diamond vendors but not so much the consumer.

Unfortunately, although the IGI brags about being the top laboratories in the trade, this may not necessarily be true.

With our knowledge in the industry, we have seen consistent inaccuracies and unreliability from the IGI.

One such jewelry insurance organization stated that certificates from the AGS and GIA are the most dependable diamond reports.

These two laboratories are reputable because of their skill and high-quality practices.

Reports issued by the GIA and AGS are not assessments and they don’t use estimations.

Certifications issued by any other laboratories are inaccurate and therefore diamond insurers shouldn’t consider them.

What’s more, Dateline raised some serious issues about IGI’s ethics back in 2005 about their grading.

As mentioned before we advise using GIA and AGS for diamond certification.

Furthermore, you should only buy diamonds from trustworthy retailers that provide GIA and AGS certificates with their stones.

Purchasing a diamond that has an independent lab certificate will guarantee grading accuracy.

You can rest assured the information on the report is accurate.

With our many years of practice in the diamond industry, we know the IGI simply can’t provide a guarantee on accuracy.

A practical example may assist you with understanding.

Imagine we send four diamonds to different laboratories including the IGI, GSI, HRD and EGL for color & clarity ratings.

This would give us a clearer understanding of how the IGI grade their stones since color and clarity are subjective categories.

IGI ratings on the four diamonds can be:

  • 1: Clarity rating of SI1 and color G

  • 2: Clarity rating of SI2 and color F

  • 3: Clarity rating of SI1 and color F

  • 4: Clarity rating of SI1 and color H

4. European Gemological Laboratory Certification

The European Gemological Laboratory (EGL) has always bragged about the quality of their diamond grades.

When you get an EGL certificate with your gem you’ll believe you’ve struck a bargain.

But really, you’ll obtain a low-quality diamond at a higher price because of the certification.

We witness countless customers buying stones certified by the EGL believing they’ve got a high-quality diamond.

People are too late to realize the con in buying a lower grade stone.

Don’t fall for the same scams.

Contact us so we can assist you with your buying decision.

Here’s a classic example of an EGL scam.

Take an EGL certified diamond with a 1.00 carat, H color grading with a VSI clarity and ideal cut at $4,450.

At first glance, this seems like an amazing bargain.

You’ll notice even though the certificate shows the diamond is H color with VSI clarity and ideal cut it has a lower grade.

You’ll find the diamond is actually a J color with an SI1 rating.

Sometimes it can be a K SI1 or J SI2 rating.

Look for a diamond with a GIA certificate with two or three color or clarity grades lower.

This guarantees the quality of your diamond at a lower price.

Overall, you shouldn’t buy a gem with an EGL certification.

It doesn’t matter how low the price is.

Compared to the reputation of a GIA certification the EGL grades are simply a marketing gimmick.

You’ll notice that EGL certifies stones as more expensive compared to the grading done by GIA.

For more evidence on the matter, let’s say we send the same four diamonds to the EGL to get ratings on their color and clarity.

As expected the EGL grades the diamonds higher than the previous laboratories we sent them to.

An EGL certified diamond with a rating of VS2 isn’t the same as a GIA VS2 grading. Therefore the quality and price of the EGL diamond aren’t equal to the stone with GIA certification.

Furthermore, the two laboratories that rate gems often give different information.

The discrepancies in the results make it extremely difficult to have faith in the quality and price of diamonds graded by the EGL.

See for yourself in the examples below:

Diamonds rated by EGL:

  • 1: Color H with clarity SI1

  • 2: Color G with clarity SI1

  • 3: Color E with clarity SI1

  • 4: Color G with clarity VS2

Diamonds rated by EGL Israel:

  • 1: Color H with clarity SI1

  • 2: Color F with clarity VS2

  • 3: Color F with clarity SI1

  • 4: Color F with clarity VS2

5. Hoge Raad Voor Diamant Certification

The Hoge Raad Voor Diamant (HRD) is a European organization.

HRD says it’s one of the top diamond rating labs in the world but the USA doesn’t regard them in this light.

For many years we’ve experienced problems with the rating quality of the HRD.

This laboratory typically increases the clarity and color grading by two levels compared to the GIA.

Diamonds rated by the HRD have a higher price compared to equal diamonds graded by the GIA.

It simply allows diamond retailers to gain a large profit on their stones.

To test the grade quality of the HRD one can send the four diamonds to the laboratory.

You’ll see that the HRD gives a higher clarity and color grading to these four diamonds compared to the GIA.

The F color grading provided by the HRD doesn’t carry the same meaning as an F color rating from GIA.

The HRD certified diamond won’t have the same price or value as the GIA rated gem even if the grades are two or three ratings higher.

HRD graded diamonds:

  • 1: Color H with clarity SI1

  • 2: Color F with clarity SI1

  • 3: Color G with clarity SI2

  • 4: Color G with clarity SI1

Reconsider your purchase if you are looking at a stone certified by the HRD.

Again we suggest you only purchase gems certified by the AGS and GIA.

6. Gemological Science International

Next we have the Gemological Science International (GSI).

Ths GSI is new in the industry and came onto the scene in recent years.

Regrettably, the GSI didn’t enter the trade with state of the art technology or new ideas.

GSI appealed to big-time diamond retailers in the USA namely Zales, Jared The Galleria of Jewelry and Kay.

Gaining the approval of these vendors meant a large profit for them.

The Capital Forum States that the GSI took Sterling’s business away from IGI.

GSI opened a laboratory near IGI’s headquarters so they could significantly reduce their pricing.

We’ve experienced that GSI grading is slacker than gold standards of GIA and AGS labs.

Also, it’s weaker than a grade level down for ratings IGI and HRD offer.

The GSI isn’t consistent with its grading.

Because of these facts, we don’t advise buying diamonds with a GSI certification.

Rather buy gems that have an AGS or GIA certificate.

With certificates from reputable laboratories such as AGS and GIA, you’ll know exactly what you’re buying.

Diamond vendors don’t use the GSI so they can provide a bargain for their customers.

They simply use inaccurate lab results so they can gain a profit.

To further reveal how GSI grades their stones compared to other laboratories we once again send through four gems so they can rate them.

You can expect to get different results on subjective categories such as the color and clarity grades.

GSI graded diamonds:

  • 1: Color I with clarity SI1

  • 2: Color H with clarity SI1

  • 3: Color G with clarity SI2

  • 4: Color H with clarity SI1


Is diamond certification vital?

A diamond certification is highly important because it confirms the value and quality of the stone.

Without an accurate certificate from a laboratory, you can’t confirm the gem you’re buying has the value the retailer claims it has.

Diamond certification includes the color, carat weight, cut quality and other important information about the stone.

With a huge purchase such as an expensive diamond, it’s crucial that you receive a certificate with your gem.

Do I really need that diamond certificate?

Yes, you must get a certificate with your diamond to know the value of your gem.

A certificate is essentially a proof of a diamond’s color, carat weight and clarity.

Without your diamond certificate, there’s no way to know if your stone is counterfeit or real.

Is there a difference between non-certified and certified gems?

A diamond is certified by third-party laboratories therefore it comes with documentation. Stones that don’t have documentation haven’t been certified by a lab.

Diamonds that have been certified give you peace of mind because it has been evaluated by professional gemologists.

It would be difficult to know the true color,

clarity and carat weight of a non-certified diamond.

We suggest you only purchase diamonds graded by reputable laboratories namely GIA and AGS.


It’s important that you only purchase diamonds graded by the AGS and GIA laboratories.

These laboratories are reputable, reliable and their gradings are always consistent.

Our company only works with trusted retailers.

Do you have questions about diamond certification?

We are here to assist you. Contact us when you want to purchase a valuable gem. We’d be happy to help you with your purchase.

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Dianoche PTE Ltd. is a diamond manufacturer registered in Singapore, as well as a diamond jewellery retailer. Our company is comprised of veterans in the world of diamonds and high-end jewellery.

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