What GIA's 2,665-Piece Inclusion Collection Teaches Lab-Grown Diamond Buyers About Reading Clarity Grades in 2026

GIA acquired a collection of 2,665 crystals, gems, and minerals with notable inclusions — assembled over 60 years by GIA Analytical Microscopist John Koivula — and the timing could not be more instructive for lab-grown diamond buyers navigating a grading space that changed on October 1, 2025.

The collection, announced in November 2026, includes foreign minerals, trapped fluids, and structural characteristics captured in specimens that GIA Museum curator Terri Ottaway described as irreplaceable: "This one-of-a-kind assemblage could not be reproduced today, not only because many of the pieces are unique, but also because specimens of comparable quality are unlikely ever to be found again." Select pieces will debut at the AGTA Tucson GemFair and the Tucson Gem and Mineral Show in February 2027.

For a buyer shopping for a lab-grown diamond ring today, this news is not merely academic. It is a reminder that clarity grading is grounded in decades of physical reference material — and that understanding what inclusions actually are gives you a decisive edge when reading any grading document, whether it is a detailed IGI report or GIA's newer, compressed format.

How the two main grading systems compare for lab-grown diamonds right now

Before diving into what inclusions are and why the Koivula collection matters, here is the practical landscape every lab-grown diamond buyer faces in late 2026:

Feature	GIA (post-Oct 2025)	IGI	GCAL
Clarity grade format	Premium or Standard (no specific grade)	FL–I3 scale (full 4Cs)	FL–I3 scale (full 4Cs)
Color grade format	Premium or Standard (no specific grade)	D–Z scale (full 4Cs)	D–Z scale (full 4Cs)
Cut grade (round brilliants)	Excellent (Premium) / Very Good (Standard)	Full scale	Full scale
Girdle inscription	"Laboratory-Grown" + assessment number	Lab report number	Lab report number
Minimum stone size	0.15 ct	0.15 ct	0.18 ct
Fee structure	$15/ct ($15 minimum); $5 if ungraded	Per-stone fee	Per-stone fee
Clarity plot diagram	Not included	Included on full reports	Included
Report verification	gia.edu/report-check	igi-usa.com	gcalusa.com

This table is the starting point for any lab-grown diamond purchase in 2026. The rest of this article explains what sits behind those grades — and why GIA's inclusion collection is the scientific bedrock that makes any grading system credible.

What exactly is an inclusion, and why does it affect a diamond's grade?

A clarity characteristic is any internal feature (inclusion) or surface feature (blemish) that affects the relative absence of clarity in a diamond. GIA's own grading documentation defines clarity grade as "the relative absence of inclusions and blemishes, graded on a scale from Flawless to Included based on size, nature, number, position, and relief of characteristics visible under 10x magnification."

That five-factor framework — size, nature, number, position, relief — is not arbitrary. It was built on exactly the kind of physical reference material that Koivula spent 60 years assembling. The new GIA collection includes a fan of mica in tourmaline and an inclusion of fluorescent petroleum fluid in quartz. One photomicrograph shows a negative crystal in quartz containing a methane bubble, dark spots of a solid hydrocarbon, water, and fluorescent petroleum, all within a field of view of just 2.17 mm. These specimens are teaching tools that train gemologists to recognize what they are looking at under magnification.

GIA confirms that lab-grown diamonds have their own distinct characteristics, including inclusions and other features, which allow GIA scientists to distinguish them from natural diamonds. Critically, "these clarity characteristics are evaluated using the same universally recognized scale and terms as those of natural diamonds — with the number, size, relief, nature, and position of the inclusions being taken into account in evaluating clarity." The scale is identical. What differs is the output format of the report.

This distinction matters enormously for buyers. When you see "VS clarity" on an IGI report for a lab-grown diamond, or "Premium" on a GIA assessment, both judgments were made by a trained gemologist using a loupe or microscope calibrated to 10x magnification, comparing what they see against reference standards built from physical specimens — specimens of exactly the type Koivula spent his career collecting.

Why did GIA change its lab-grown diamond grading system in October 2025?

GIA's stated rationale is a clustering argument. As Lily Dia's analysis of the change explains, GIA's Chief Laboratory Officer Tom Moses put it this way: "More than 95% of laboratory-grown diamonds fall into a very narrow range of colour and clarity, so it's no longer relevant to use the nomenclature created for natural diamonds."

HPHT and CVD growth happens in controlled chambers, and the output clusters tightly inside D to H color and VS1 or better clarity. When 95% of stones sit in roughly the same band, a five-letter color grade and a six-tier clarity grade stop differentiating one stone from another in any commercially meaningful way. A broader, cheaper assessment fits how the market actually prices these diamonds now — lab-grown prices have dropped sharply over the last few years, and a detailed GIA report on a small lab-grown stone often cost more than the stone itself was worth.

Montare Diamonds' detailed breakdown of the new system is precise about what Premium and Standard actually require:

Premium requires D color, VVS clarity or higher, Excellent polish, Excellent symmetry, and — for round brilliants — an Excellent cut grade. Every factor must hit the top tier simultaneously.
Standard covers E through J color, VS clarity, Very Good polish and symmetry (Good accepted on some fancy shapes), and at least a Very Good cut grade on round brilliants.
Diamonds that fall below Standard receive no classification at all; GIA charges a $5 evaluation fee and returns the stone ungraded.

Reports issued before October 1, 2025 remain valid. A GIA lab-grown report from 2023 with specific color and clarity letters on it has not been retroactively reclassified.

What does the GIA inclusion collection have to do with reading a lab-grown diamond report?

The connection is more direct than it appears. Koivula joined GIA in 1976 and is known for his photomicrography work, including the introduction of fiber-optic illumination in gem research — a technique now common in gem labs worldwide. The photomicrographic methods he pioneered are the same methods used today to document clarity characteristics on every GIA report.

The INSTORE report on the acquisition notes that the collection has been cataloged in a custom database and will support GIA's education programs, gemological research, and gem identification and origin services. GIA senior vice president Cathryn Ramirez said: "Generations of students, gemologists and scientists will benefit from his incredible contributions to gemology."

For a lab-grown diamond buyer, this translates into a simple principle: the clarity grade on any reputable lab report is only as good as the training of the gemologist who assigned it, and that training depends on reference collections exactly like this one. When you read "VS clarity" or "VVS" on an IGI report, or "Premium" on a GIA assessment, you are reading the output of a system calibrated against physical specimens over decades.

Understanding this chain of evidence helps buyers ask better questions. Rather than accepting a grade at face value, you can ask: what specific clarity characteristics are listed? Where are they located? Are they in the table (the flat top facet, where they are most visible) or near the girdle (where they are harder to see)?

How do you read the clarity section of a GIA report for a natural diamond — and why does it still matter for lab-grown buyers?

Even though GIA no longer issues specific clarity grades for lab-grown diamonds submitted after October 2025, understanding the full GIA report format remains essential for two reasons. First, millions of pre-October 2025 lab-grown diamonds with full GIA 4Cs reports are still in circulation and on the resale market. Second, IGI — which certifies the large majority of lab-grown diamonds sold today — still uses the full 4Cs format, and reading that format requires the same literacy as reading a GIA natural diamond report.

GIA's Diamond Dossier guide defines the key fields as follows:

Clarity Grade (Field 7): The relative absence of inclusions and blemishes, graded on a scale from Flawless to Included based on size, nature, number, position, and relief of characteristics visible under 10x magnification.

Clarity Characteristics (Field 12): A list of the most significant clarity characteristics present in the diamond that justifies the clarity grade. A maximum of four characteristics are listed. On a GIA Dossier for a 0.67-carat round brilliant graded SI2, for example, the clarity characteristics field might read "Crystal, Feather" — meaning the two most significant inclusions are a crystal (a mineral trapped inside the diamond during growth) and a feather (a small fracture).

Diamond Critics' field guide to GIA reports identifies the single most overlooked field as the Comments section: "Clarity based on clouds not shown" on a clarity report means the diamond has diffuse internal haziness that GIA did not draw on the plot because the cloud has no distinct boundary. This is a red flag that a buyer reading only the headline clarity grade would miss entirely.

The proportions table — table percentage, depth percentage, crown angle, pavilion angle — determines whether a GIA Excellent cut stone has ideal optical performance or merely mediocre-within-Excellent performance. A stone can carry an Excellent cut grade and still underperform optically if its proportions sit at the edges of the Excellent range.

What clarity characteristics are specific to lab-grown diamonds?

Lab-grown diamonds grown by the CVD (chemical vapor deposition) method and the HPHT (high pressure, high temperature) method each produce characteristic inclusion types that differ from those found in natural diamonds — and from each other.

CVD diamonds commonly show graining (internal strain patterns), pinpoints, and occasionally small graphite inclusions from the carbon source. HPHT diamonds may contain metallic flux inclusions — tiny particles of the iron, nickel, or cobalt catalyst used in the growth process — which are magnetic and can be detected with a strong magnet. Neither inclusion type is inherently dangerous to the stone's durability; both are simply the fingerprints of how the diamond was made.

GIA confirms that these lab-grown-specific characteristics "allow GIA scientists to distinguish them from natural diamonds." This is one reason why GIA's inclusion collection — which now encompasses not just gem minerals but the full range of trapped fluids and structural characteristics — is directly relevant to lab-grown diamond identification. The more reference material gemologists have, the more accurately they can identify what they are looking at.

For buyers, the practical implication is that a VS1 clarity lab-grown diamond and a VS1 clarity natural diamond carry the same grade on the same scale, but the nature of the inclusions causing that grade may be completely different. Knowing the difference helps you evaluate whether the inclusions are eye-visible, whether they affect brilliance, and whether they sit in a position that makes the stone vulnerable to chipping.

Should you choose GIA or IGI certification for a lab-grown diamond in 2026?

This is the most common practical question buyers face, and the answer depends on what you need from the grading document.

If you want maximum detail — specific color letter, specific clarity grade, a clarity plot diagram showing where inclusions are located — IGI is currently the only major lab offering that for new lab-grown diamond submissions. GCAL and HRD Antwerp also continue to grade lab-grown diamonds on the full 4Cs scale.

If you want the prestige of a GIA document and are comfortable with the Premium/Standard format, GIA's assessment is a legitimate and credible option. The girdle inscription reading "Laboratory-Grown" plus a unique assessment number means the stone is verifiable at gia.edu/report-check, and the grading methodology behind the Premium/Standard classification uses the same gemological rigor as GIA's natural diamond reports.

Lily Dia's analysis notes that if you want the level of detail in writing that GIA used to provide, "you'll need IGI, GCAL or HRD Antwerp, all of which still grade lab-grown diamonds on the full 4Cs." The price differential between GIA and IGI lab-grown grading is smaller than for natural diamonds, and both labs use consistent standards for lab-grown stones.

Montare Diamonds' breakdown makes the limitation of the new GIA format concrete: "A two-letter label can't tell you if a stone is D or E colour, or VVS1 versus VVS2." For buyers with a specific quality floor in mind — say, D–E color and VVS1–VVS2 clarity — an IGI report with individual grades gives you verifiable confirmation. A GIA Premium label tells you the stone is at least D color and VVS clarity, but not whether it is D/Flawless or D/VVS2.

How do you verify a lab-grown diamond report before buying?

Verification means confirming that a grading document is authentic, that the report number matches the stone in hand, and that the grading details on the document match the stone's actual characteristics.

For GIA documents, verification is done at gia.edu/report-check using the report number. Every legitimate GIA stone has a verifiable digital record. Diamond Critics' guide is direct: "Before paying a deposit, verify the report number is active and matches the stone description. Any discrepancy = walk away."

For IGI documents, verification is done at the IGI website using the report number. The same principle applies: the number on the document should match the number inscribed on the girdle of the stone, and the stone's measurements should match those listed on the report.

The Koivula collection reinforces why this verification step matters. His specimens are cataloged in a custom database — a physical and digital reference system that underpins GIA's ability to identify and grade stones accurately. When you verify a report number, you are connecting your purchase to that entire chain of scientific reference.

What will the Koivula collection mean for gemological education going forward?

Koivula and colleagues are preparing a large-format book of photomicrographs of the specimens, which will extend the collection's reach beyond GIA's physical campus. The collection will support GIA's education programs, gemological research, and gem identification and origin services, and it expands GIA's gemological reference collection.

For lab-grown diamond buyers, the downstream effect is better-trained gemologists. Every gemologist who uses the Koivula collection as a teaching reference will be better equipped to identify the specific inclusion types that distinguish CVD from HPHT growth, to recognize the structural characteristics that affect clarity grades, and to apply the five-factor framework — size, nature, number, position, relief — with greater precision.

This matters because the clarity grade on your lab-grown diamond report is not a number generated by a machine. It is a judgment made by a human expert, calibrated against physical reference material. The fuller that reference material, the more reliable the judgment.

What should a lab-grown diamond buyer actually do with this information?

The practical checklist for a lab-grown diamond buyer in late 2026 comes down to five steps.

First, decide which grading format you need. If you want specific color and clarity grades for a new lab-grown diamond, choose a stone certified by IGI, GCAL, or HRD Antwerp. If you are comfortable with GIA's Premium/Standard format, verify that the stone meets the Premium threshold if top-tier quality is your goal.

Second, read the clarity characteristics field, not just the clarity grade. On an IGI report, this field lists the specific inclusion types and their locations. A crystal near the table is more visible than a feather near the girdle. Position matters as much as grade.

Third, check the comments section. "Clarity based on clouds not shown" is a warning that the stone may appear hazy despite its clarity grade — the most commonly overlooked field on any diamond report.

Fourth, verify the report number before completing any purchase. Use the relevant lab's online verification tool and confirm the number matches the girdle inscription on the stone.

Fifth, understand that the grading system behind any reputable lab report is built on decades of physical reference material — exactly the kind that GIA's acquisition of the Koivula collection preserves and extends. A clarity grade is not an abstract label; it is the output of a scientific process grounded in specimens that took 60 years to assemble.

For buyers considering lab-grown diamond engagement rings, our guides to best lab-grown diamond engagement rings in India and oval lab-grown diamond solitaire rings include clarity grade recommendations specific to each stone shape and setting style — because an inclusion invisible in a round brilliant may be clearly visible in an oval cut, where the elongated facet pattern distributes light differently.

The Koivula collection is a reminder that the science behind clarity grading is cumulative, irreplaceable, and directly connected to the document you receive when you buy a lab-grown diamond. Reading that document well is the single most underused skill in the buying process.