Every serious engagement ring purchase should come with paperwork — specifically, a diamond grading report issued by an independent gemological laboratory. At Pure Brilliant Jewels, we ship every piece with a certificate from the International Gemological Institute (IGI). But what does that certificate actually mean, and why should you care?
In this guide, we explain what IGI is, what its grading report covers, how to read one, and why certification is the most important protection you can have when buying a lab-grown diamond.
What Is IGI?
The International Gemological Institute is one of the world's largest and most respected independent diamond grading laboratories. Founded in 1975 in Antwerp — the global diamond capital — IGI now operates labs on multiple continents and has graded tens of millions of diamonds.
IGI is a third party: it does not buy, sell or mine diamonds. Its sole job is to examine stones under controlled conditions and report their characteristics objectively. That independence is exactly why consumers trust it — the laboratory has no incentive to overstate a diamond's quality.
IGI was also a pioneer in grading laboratory-grown diamonds and clearly identifies a stone's origin on every report, giving the consumer full transparency about whether their diamond is grown or mined.
What Does an IGI Certificate Grade?
An IGI report documents the "4Cs" — the universal language of diamond quality:
- Carat Weight: the diamond's weight in carats and in points, measured to high precision.
- Color: a grade from D (colorless) down through the alphabet to Z (light yellow). For lab-grown diamonds, most reports show near-colorless D–F stones.
- Clarity: an assessment of inclusions and surface blemishes, from Flawless down to Included. Grades like VS1, VS2 and SI1 are the common sweet spots for engagement rings.
- Cut: an evaluation of proportions, symmetry and polish that determines brilliance. Exceptional and Very Good grades are what you want for maximum sparkle.
Beyond the 4Cs, a full IGI report also records measurements, fluorescence, and — critically for lab-grown stones — the growth method (HPHT or CVD) and a statement that the diamond is laboratory-grown.
Why Certification Protects You
Without an independent certificate, you're trusting the seller's word alone. Certification changes the game in four ways:
- Verification: an accredited lab confirms the stone is exactly what it claims to be — including whether it's genuinely lab-grown diamond rather than a simulant.
- Fair pricing: you can compare like-for-like. Two diamonds with the same IGI grades are directly comparable, so price differences are meaningful rather than mysterious.
- Dispute resolution: if anything is ever questioned, the certificate is an objective reference point documented by a neutral party.
- Resale and insurance: insurers and future buyers usually want documentation; a certificate makes insuring or eventually passing on the piece straightforward.
As a rule: if a diamond isn't accompanied by a lab report, walk away or ask why. Especially with lab-grown stones, the certificate is the only proof of what you're receiving.
How to Read an IGI Report
An IGI certificate looks technical, but its key lines read quickly once you know what to look for:
Shape & Cut Grade
The report states the cutting style (e.g., Round Brilliant, Oval Brilliant, Princess) and a cut grade. Aim for the top cut grades — they drive sparkle.
Color Grade
A letter from D to Z. In 14K gold settings, stones graded G–I look stunning; in white metals, G or above is a safe bet.
Clarity Grade
Letters describing flaw visibility: FL/IF (flawless), VVS1/VVS2 (very very slightly included), VS1/VS2 (very slightly included), SI1/SI2 (slightly included). VS2 and above are eye-clean — the standard choice.
Origin Statement
For lab-grown diamonds the report explicitly says "Laboratory-Grown" and notes the growth method. This transparency is a hallmark of IGI's approach and protects the buyer absolutely.
If you'd like specifics on any stone you're considering, send us a message — we'll walk you through the certificate line by line.
IGI vs. GIA: Which Is Better?
The Gemological Institute of America (GIA) is IGI's most famous competitor, best known for grading natural diamonds. Both are respected, accredited, independent laboratories. The practical differences:
- Consistency and timeline: IGI grades a massive volume and is known for accurate, consistent 4Cs evaluation — makes it a favorite of jewelers worldwide.
- Lab-grown expertise: IGI was among the first to robustly certificate lab-grown stones and labels them clearly — a big advantage for lab-diamond buyers.
- Price implications: GIA-graded natural stones sometimes command a small premium in resale circles. For lab-grown diamonds, IGI certification is widely standard and perfectly protective.
Both protect you well. We choose IGI because of its accuracy, its leadership in lab-grown grading, and the fact that its certificates are recognized by insurers and secondary buyers worldwide.
What IGI Does NOT Tell You
A certificate grades the stone; it does not evaluate the craftsmanship of the ring that holds it. Prong security, metal quality and overall design are our responsibility — which is why we handcraft every setting in solid 14K gold and stand behind the work with our lifetime guarantee. Buy the best stone you can afford certified, and pair it with well-made jewelry; the certificate covers the one, our craftsmanship covers the other.
How IGI Certifies a Stone
Understanding the process behind the certificate builds confidence in what it means. When a diamond arrives at an IGI laboratory, it undergoes a systematic examination:
- Weighing & measuring: the stone is weighed to a thousandth of a carat and measured precisely to build its geometric profile.
- Color grading: the diamond is compared against a master set of color reference stones in controlled lighting, from faces up and faces down, to determine its letter grade.
- Clarity grading: under 10x magnification a grader maps every inclusion and blemish, notes its size, position and visibility, and assigns a clarity grade.
- Cut evaluation: proportions, angles, symmetry and polish are measured, factoring in table size, depth, crown angle, girdle thickness and pavilion depth to assess light performance and assign a cut grade.
- Origin and growth assessment: for lab-grown stones, advanced testing confirms that the diamond was created in a laboratory and records the growth method (HPHT or CVD).
Nothing about this process passes through the seller's hands. The lab's independence is the entire point of the certificate — the grader has no stake in whether the diamond is overstated or understated.
Understanding Table Size, Depth & Proportions
A grading report's proportions section can feel like a math test, but a few numbers matter more than the rest:
- Table percentage: the size of the flat top facet relative to the stone's width. Sweet spots vary by shape, but a modern round typically sits around 53–58%.
- Total depth percentage: the stone's height as a percentage of its width. A round diamond usually falls around 59–62%. Too shallow and the stone looks dark; too deep and carat weight hides below the girdle.
- Crown angle & pavilion angle: the angles of the top and bottom facets that work together to produce brilliance. When they're well-matched, light returns brightly; when mismatched, light leaks out the bottom.
You do not need to memorize these — the cut grade on the report is the summary you should trust. But next time you compare two reports, comparing table and depth will tell you instantly how they differ.
Fluorescence: Should You Care?
Fluorescence is a glowing effect some diamonds show under ultraviolet light (like nightclub blacklights or strong sunlight). Reports note it as None, Faint, Medium, Strong or Very Strong.
The practical guidance is simpler than the scare stories suggest. Faint or medium fluorescence is usually harmless and invisible in daily wear; in some slightly lower-color stones it can even make the diamond appear whiter. Very strong fluorescence is a legitimate reason to pause — it can make a stone look milky or hazy. For the near-colorless lab-grown diamonds we set, fluorescence is rarely a factor at all. The report gives you the information; the rule of thumb is to note it but fear only the extremes.
Certificate vs. Jewelry Appraisal
A common point of confusion: a grading certificate is not the same document as a jewelry appraisal. The IGI report describes the diamond's characteristics objectively. An appraisal is a valuation — it estimates what the finished ring (stone plus gold plus craftsmanship) is worth for insurance or resale purposes.
For an engagement ring you'll want both. The certificate documents the stone; the appraisal assigns a replacement value for your homeowners' or jewelry insurance. Ask us when ordering and we can point you toward getting the right coverage for your finished piece.
Common Questions About IGI Reports
"Are IGI reports recognized internationally?"
Yes. IGI operates laboratories worldwide and its reports are accepted by insurers, retailers and secondary markets across North America, Europe, Asia and the Middle East.
"Can I verify a certificate online?"
Yes — IGI maintains a searchable database where you can confirm a certificate's number and details, adding one more layer of protection against any forged document.
"Do I need IGI for a half-carat stone?"
Certification matters at every size. Even smaller lab-grown diamonds deserve documented quality, particularly because growth origin should be disclosed. Let our team know the details when you choose a piece and we'll include the supporting report.
How the 4Cs Interact on the Ring
A certificate tells you steer in isolation, but real-world beauty is about how the grades work together — especially against your chosen metal.
In yellow gold, slightly lower color grades (G–I) vanish into the warm metal and appear perfectly white, so you can save money without visible difference. In white gold or platinum, the bright metal reflects more light around the stone, so near-colorless (G or above) is the safer bet to avoid any warm hint in the stone.
Clarity tells a similar story. Since inclusions usually only appear under magnification, an eye-clean VS2 stone in a lovely halo setting can match a higher-graded stone that cost twice as much. Read the report to confirm eye-cleanliness, then spend the savings on a larger stone or a finer band — the ring's overall beauty will benefit more than a one-grade clarity bump ever would.
Why Carat and Cut Deserve Equal Attention
Shoppers tend to stare at the carat number first — it's the most intuitive. But two identical-weight stones can differ wildly in beauty if their cut grades differ. A larger, badly cut diamond looks dark and lifeless beside a smaller, brilliantly cut one.
The practical reading: prioritize an Excellent or Very Good cut before chasing carat weight. Then use the budget you've freed by choosing lab-grown to step up both weight and setting at once. Our engagement ring guide dives deeper into exactly how to balance these trade-offs.
What the Numbers Mean for Your Piece
Here's how to apply what's on a certificate to what's in the box:
- Cut Excellent/Very Good: brilliant, lively stone — the strongest predictor of everyday beauty.
- Color D–F: colorless; G–H: near-colorless and an excellent value in gold.
- Clarity VS2 and above: eye-clean — your bare eye sees no flaws.
- Origin: Laboratory-Grown: disclosed and confirmed — full transparency on how your diamond was made.
When in doubt, ask. Every piece in our collection ships with its IGI certificate, and we're happy to walk you through the exact grades on the piece you're considering before you commit.
Paperwork as Peace of Mind
At the end of the day, a certificate is trust you can hold. It upgrades a purchase from "I hope this is what I paid for" to "I know exactly what I bought." For an object that will be worn, insured and passed down for generations, that certainty is priceless. Read the report once, understand the four simple grades, and keep it safe with the box — it's the documentation of your diamond's story.
Our Promise
Every diamond we set — from our sparkling halos to our solitaire, three-stone and eternity designs — is IGI-certified and hand-set in 14K gold. When your piece arrives, its certificate travels with it. No guesswork, no ambiguity, just transparent quality you can read, verify and trust.
Interested in learning more about the stones behind the certificate? Compare your options in lab-grown vs natural, or visit the lab-grown diamond FAQ for fast answers.