IGI ( International Gemological Institute ) and SGL ( Solitaire Gemmological Laboratories ) are both well known gemological laboratories that provide independent grading reports for diamonds . A certificate does not make a diamond better or worse, it is an unbiased assessment of the diamond's qualities, namely its cut, colour, clarity and carat weight. Buying diamond jewellery and choosing a certified diamond makes you more confident on what you are buying.
Table of Contents
- What Is a Diamond Certificate?
- Why Certification Matters
- What Is IGI?
- What Is SGL?
- IGI vs SGL Comparison
- What Information Does a Certificate Include?
- How to Verify a Certificate
- Which Certification Should You Choose?
- FAQs
Introduction
When you are shopping for diamond jewellery, you often come across the terms IGI Certified or SGL Certified.
These acronyms can be confusing to first-time buyers.
Is one certificate better than the diamond?
Should you buy IGI only?
Is SGL legit or scam?
The answer is actually a lot easier than a lot of people think.
A diamond certificate is not an upgrade in quality.
It’s an independent report that grades the diamond and describes its characteristics so buyers know exactly what they are buying.
Certification helps build confidence and transparency whether you choose lab grown or natural diamonds.
What Is a Diamond Certificate?
A diamond certificate (or grading report) is an independent document issued by a gemological laboratory after examining a diamond.
The laboratory then grades the diamond based on standard grading procedures and records its characteristics.
A typical certificate contains:
- Carat Weight
- Cut Grade (where applicable)
- Colour Grade
- Clarity Grade
- Measurements
- Polish
- Symmetry
- Fluorescence (if applicable)
- Laser Inscription Number (if available)
Consider the certificate as the diamond's identity document. It does not give a value or price but it gives a standardised description of the quality of the diamond.
Why Is Certification Important?
The certification process gives buyers confidence because it provides an independent evaluation of the diamond, instead of relying solely on a retailer’s description.
Advantages:
- More transparency.
- Easier to compare diamonds
- Vendor-independent quality confirmation.
- Useful documentation for insurance or future valuation.
- More confidence to buy online.
Certification is an important part of the buying process, especially for lab grown diamonds.
What Is IGI?
IGI (International Gemological Institute) is one of the world's leading independent gemological laboratories.
IGI, founded in 1975 grades natural and lab grown diamonds and has laboratories in several countries.
IGI grading reports are recognized throughout the global jewellery industry.
A report of IGI usually contains:
- Size of diamond Shape
- Carats (weight in)
- Colour grading
- Clarity of grade
- Cut grade (round brilliant diamonds)
- Symmetrie Fluoreszenz
- Details of laser inscription (if applicable)
Because of its international presence, shoppers are well aware of IGI certification, particularly for lab grown diamonds.
What Is SGL?
SGL (Solitaire Gemmological Laboratories) is an established gemological lab that provides grading reports on Diamonds and Diamond Jewellery.
SGL certificates also assess the diamond’s main features based on widely accepted grading standards in the industry.
Depending on the report type, an SGL certificate may include:
- Carat weight
- Shape
- Colour
- Clarity
- Measurements
- Finish characteristics
- Identification details
SGL certified diamonds are now widely available in the Indian jewellery market and are accepted by many retailers.
IGI vs SGL: Side-by-Side Comparison
| Feature | IGI | SGL |
|---|---|---|
| Independent grading | ✔ | ✔ |
| Grades lab grown diamonds | ✔ | ✔ |
| Grades natural diamonds | ✔ | ✔ |
| Reports cut, colour, clarity & carat | ✔ | ✔ |
| Laser inscription details (where applicable) | ✔ | ✔ |
| Online report verification | ✔ | ✔ |
| Widely recognised internationally | ✔ | Primarily recognised within India and by participating jewellers |
Important: The grading report describes the diamond's characteristics. It does not guarantee a resale price or determine how much a retailer will charge for the jewellery.
Does Certification Affect the Diamond's Quality?
No.
A certificate doesn’t make a diamond.
Two diamonds of the same quality will be identical, no matter which recognised laboratory issued the report.
So the certificate only has the observations made at the time of grading.
This is an important distinction as many first-time buyers mistakenly believe that one certificate automatically makes a diamond “better”.
In fact it’s the diamond itself that determines the quality. The certificate serves as an independent record of those characteristics.
How to Read an IGI or SGL Diamond Certificate
If you’ve never bought diamond jewellery before, a grading report can be daunting. The good news is that you don’t need to understand all the technical details. “You can look at a few key sections and confidently make most buying decisions.
Here’s what to look for when you’re reviewing an IGI or SGL certificate.
1. Certificate Number
Every certificate has a separate identification number.
This number enables you to:
- Online confirmation of report (if supported by issuing laboratory)
- Match your diamond to the certificate
- Check that you are receiving the certified stone in the report
Many diamonds even have this certificate number laser inscribed on the girdle, which can be seen with magnification.
BUYING TIP: Check that the certificate number on the document matches the number on the diamond (where laser inscription is available) before accepting delivery.
2. Diamond Shape
The report identifies the shape of the diamond.
Common shapes include:
| Shape | Best For |
|---|---|
| Round Brilliant | Maximum sparkle |
| Oval | Elegant appearance with an elongated look |
| Cushion | Soft, vintage-inspired style |
| Emerald | Clean lines and sophisticated look |
| Pear | Modern and distinctive |
| Princess | Contemporary square shape |
| Radiant | Combines brilliance with trimmed corners |
| Marquise | Creates the illusion of a larger stone |
The certificate records the shape—it doesn't judge which is "best". The ideal choice depends on your style.
3. Carat Weight
Carat measures the weight of the diamond, not its physical size.
Typical examples:
| Carat | Popular Use |
|---|---|
| 0.25 ct | Everyday jewellery |
| 0.50 ct | Gifts and daily wear |
| 1.00 ct | Engagement rings |
| 2.00 ct+ | Luxury jewellery |
Many first-time buyers assume bigger is always better.
In reality, a well-cut 0.70 ct diamond often appears more attractive than a poorly cut 1.00 ct diamond.
4. Colour Grade
Colour grades indicate how colourless a diamond is.
| Grade | Appearance |
|---|---|
| D–F | Colourless |
| G–H | Near colourless |
| I–J | Slight warmth |
| K+ | Increasing visible colour |
For most buyers, G–H provides an excellent balance between appearance and price.
When set in yellow or rose gold, slight warmth is often less noticeable than in white metals.
5. Clarity Grade
Clarity measures the natural internal and external characteristics of a diamond.
| Grade | Description |
|---|---|
| FL | Flawless |
| IF | Internally Flawless |
| VVS1–VVS2 | Very, Very Slightly Included |
| VS1–VS2 | Very Slightly Included |
| SI1–SI2 | Slightly Included |
Many VS and SI diamonds appear completely clean to the naked eye.
That means paying a premium for flawless clarity isn't always necessary for everyday jewellery.
6. Cut Grade
For round brilliant diamonds, cut quality has one of the biggest influences on sparkle.
Typical cut grades include:
- Excellent
- Very Good
- Good
- Fair
- Poor
If you’re budget conscious, increasing the weight of Excellent or Very Good cut has more impact on beauty than increasing carat weight.
7. Polish
Polish describes how well the diamond’s surface has been finished after it’s been cut.
Common grades:
- Excellent
- Very Good
- Good
Higher polish grade will help maximize light performance and overall looks.
8. Symmetry
Symmetry is the alignment of the facets with one another.
Well aligned facets help light to better reflect through the diamond.
Most buyers can expect, at worst, Very Good or Excellent symmetry.
9. Measurements
Each certificate gives the size of the diamond exactly.
Typically, round diamonds are measured as follows:
6.45 x 6.48 x 3.95 mm
These measurements allow experts to evaluate the proportions of the stone and confirm its identity.
10. Laser Inscription
Many certified diamonds have a microscopic laser inscription on the girdle.
This inscription usually reads:
- Certificate no.
- Laboratory identification
- Further identification information
It also offers another way to match the diamond to its grading report.
Understanding the 4Cs in Practical Terms
You’ve heard of the 4Cs, but knowing what they are is only part of the story. Understanding which matters most can help you spend your budget more wisely.
1. Cut – The Most Important Factor
Cut affects the sparkle of a diamond.
A well cut diamond will normally appear brighter and livelier than a larger diamond with poor proportions.
Recommendation: Focus on the cut rather than increasing the carat weight.
2. Colour – Where Value Meets Beauty
Most buyers look for the best colour grade, but G–H diamonds look almost identical to colourless diamonds once set in jewellery.
You can get great value with no noticeable difference by selecting G - H.
3. Clarity – Eye-Clean Matters Most
Forget perfect grades, the question is, does the diamond look clean to the naked eye?
For a good balance of quality and budget, a VS or eye-clean SI diamond is often a practical choice.
4. Carat – Balance Size with Quality
Carat weight is eye-catching, but it’s not the only thing to consider.
Here’s how to make this:
- A well cut 0.90 ct diamond can be more brilliant than a poorly cut 1.00 ct diamond.
- A slightly smaller stone with a better cut and colour may be more attractive overall.
Buying Advice in Action
Practical Buying Advice
When comparing two certified diamonds, consider:
- Are both of them separately certified?
- Is the cut quality the same?
- Do they have a similar colour and transparency?
- Which one has the best balance of quality and price?
The certificate provides you with the information that you need to make an objective comparison rather than relying solely on product descriptions.
How to Verify an IGI or SGL Certificate
One of the biggest advantages of buying a certified diamond is that the grading report can usually be verified with the issuing laboratory.
Before purchasing, follow these simple steps:
Step 1: Ask for the Certificate
The diamond grading report should be provided with your purchase or before dispatch from a reputable jeweller.
Step 2: Check the Certificate Number
Every certificate contains a unique report number.
Make sure the number is:
- Clearly printed
- Easy to read
- Matches any laser inscription on the diamond (if applicable)
Step 3: Verify with the Issuing Laboratory
Most recognised laboratories provide an online report verification service where you can enter the certificate number to confirm that the report exists and matches the details of your diamond.
When verifying, compare:
- Carat weight
- Shape
- Colour
- Clarity
- Measurements
If these details match your certificate, it provides additional confidence that the report corresponds to your diamond.
Questions to Ask Before Buying a Certified Diamond
Certification is important, but it shouldn't be the only factor in your buying decision.
Ask your jeweller these questions:
Is the diamond independently certified?
The certificate obtained from a recognised grading laboratory provides an impartial assessment of the diamond.
Is the jewellery BIS Hallmarked?
BIS Hallmarking testifies to the purity of the precious metal in gold jewellery sold in India.
Can I see the grading report before purchasing?
By looking at the report you should be able to get a feel for the key quality characteristics before you decide.
Does the certificate match the product description?
The information shown on the certificate should align with the specifications listed by the retailer.
What after-sales services are available?
Ask about:
- Warranty
- Cleaning services
- Repairs
- Exchange policy
- Buyback policy (where applicable)
Common Myths About Diamond Certification
Myth 1: A Certificate Makes the Diamond More Valuable
Reality: A certificate does not improve a diamond or make it more valuable. It simply notes its characteristics after an independent assessment.
Myth 2: Only One Laboratory Can Be Trusted
Reality: There are a number of recognized gemological labs that provide diamond grading. The main thing is to know what the report contains and to buy from a reputable jeweller.
Myth 3: Certification Guarantees the Lowest Price
Reality: Certification checks quality attributes, not retail price. The jewellery prices also include metal, design, craftsmanship, making charges and after sales services.
Myth 4: Certified Diamonds Are Always Better Than Uncertified Diamonds
Reality: Certification brings transparency, but the diamond is the ultimate arbiter of quality. Two diamonds with the same characteristics are the same whether you have a grading report or not. But certification gives buyers more confidence in what they are buying.
Why Certification Matters When Buying Online
Online jewellery shopping has become increasingly popular, but buyers cannot inspect a diamond in person before placing an order.
Certification helps bridge that gap by providing an independent description of the diamond's characteristics.
When buying online, look for:
- Independent grading report
- High-quality product photographs
- Detailed specifications
- Clear return and exchange policy
- Transparent customer support
These factors together create a more confident buying experience.
FAQ's
Is IGI certification genuine?
Yes. IGI is an internationally recognized gemological laboratory that grades both natural and lab-grown diamonds.
Is SGL certification genuine?
SGL is a reputable gemological laboratory that provides grading reports for diamonds and diamond jewellery. It is widely used in the jewellery market of India.
Is IGI better than SGL?
Neither certificate automatically makes a diamond better. The most important factor is the quality of the diamond itself. A recognised grading report from either laboratory provides independent information about the stone's characteristics.
Does certification affect resale value?
Certification can make future valuation or exchange easier because it provides documented information about the diamond. However, resale or exchange values depend on multiple factors beyond the certificate itself.
Can a certificate be forged?
Like many important documents, fraudulent copies can exist. This is why buying from a reputable jeweller and verifying the certificate with the issuing laboratory is recommended.
Should every diamond be certified?
For significant diamond purchases, an independent grading report offers valuable transparency and helps buyers compare diamonds more confidently.
Does a certificate include the jewellery?
Most grading reports describe the diamond. Some reports will also include details of the jewellery depending on the issuing laboratory and type of report.
What happens if I lose my certificate?
Ask your jeweller for advice. Options might exist for obtaining replacement documentation or verifying the report by its unique number depending on the issuing laboratory and original report.
Expert Buying Tips
If you are choosing between two certified diamonds:
- Buy the biggest carat weight you can afford but give priority to cut quality.
- Look at the color and clarity together and not at one grade alone.
- Read the entire certificate, not just the headline specs.
- Make sure the product description corresponds to the grading report.
- Buy from a jeweller who gives you clarity on certification, hallmarking, warranty and after sales support.
Related Guides
Continue learning with these guides:
- Lab Grown vs Natural Diamond Price in India
- Do Lab Grown Diamonds Have Resale Value?
- How Much Does a 1 Carat Lab Grown Diamond Ring Cost in India?
- BIS Hallmark Explained
- 925 Silver vs 14K Gold for Diamond Jewellery
Recommended Collections
Explore our certified jewellery collections:
- Lab Grown Diamond Rings
- Diamond Earrings
- Diamond Pendants
- Diamond Necklaces
- Men's Diamond Ring
- Best Sellers
Final Thoughts
There is no “winner” in the choice between IGI and SGL. It is about understanding what a grading report is saying and using that information to make a good decision.
A certified diamond provides clarity, makes it easier to compare diamonds and adds confidence to your shopping experience online or in-store. Certification, Clear product information, BIS Hallmarking (where applicable) and a transparent exchange and after-sales policy are key to a trustworthy jewellery buying experience.
Whether the diamond is graded by IGI or SGL, the important thing is that the jewellery meets the quality of the description, is supplied from a reputable jeweller and meets your expectations for craftsmanship and value.
