How to Compare Two Certified Lab-Grown Diamonds

Use this sequence:

1. Verify both reports through the issuing laboratories.
2. Confirm laboratory-grown origin and report type.
3. Match shape, carat weight and millimetre dimensions.
4. Compare cut, proportions and real light performance.
5. Compare colour in the intended metal.
6. Examine clarity characteristics, not only the grade.
7. Review polish, symmetry and fluorescence.
8. Check CVD or HPHT growth and post-growth treatment comments.
9. Compare videos under identical conditions.
10. Evaluate price, return policy, warranty and setting fit.

The diamond that wins the most visible and relevant categories—not simply the most paper categories—is usually the better choice for that buyer.

Before comparing grades, establish the same scope.

Compare the same product type: A loose principal diamond should not be compared directly with the total carat weight of a finished ring. Separate centre-stone weight from accent-diamond weight and setting price.

Compare similar shapes: Round and oval diamonds use weight differently. If the buyer has not chosen a shape, compare style and coverage first. If shape is fixed, compare stones within that shape.

Compare equivalent report systems: IGI commonly gives individual 4C grades for eligible lab-grown diamonds. GIA’s current qualifying colourless-to-near-colourless laboratory-grown service uses Premium or Standard overall classifications. These formats are not direct substitutes.

If the report systems differ, compare the fields actually disclosed and the real diamonds rather than translating one laboratory’s terminology into invented grades.

Compare the same price scope: Confirm whether prices include VAT, setting, delivery, resizing, certification, insurance shipping and returns. A loose-diamond price and a finished-jewellery price are not equivalent.

Do not begin with colour or clarity. Begin by establishing that each report belongs to the diamond being offered.

For each stone:

1. Use the issuing laboratory’s official report-verification database.
2. Enter the complete report or assessment number.
3. Confirm the laboratory-grown description.
4. Match shape and cutting style.
5. Match carat weight and exact measurements.
6. Compare report comments and inscriptions.
7. Ask a jeweller to locate the girdle inscription where applicable.

A report number appearing in a legitimate database proves that the record exists. It does not alone prove that a different physical stone has not been given a copied inscription. For higher-risk or secondary-market transactions, professional examination should match identifying characteristics as well. Use how to verify an IGI certificate number and what a diamond laser inscription is for the complete process.

Blank information is itself important. Ask whether the field is unavailable because of the report format, omitted from the product page or unknown to the seller.

Carat is mass, while dimensions explain visible scale. Two 1.00 ct diamonds can face up differently because of depth, girdle and shape.

For round diamonds, compare:

• minimum and maximum diameter;
• average diameter;
• total depth;
• girdle thickness; and
• whether the outline is acceptably round.

For fancy shapes, compare:

• length and width;
• length-to-width ratio;
• depth;
• outline symmetry; and
• corner or point shape.

Do not automatically choose the widest diamond. Extra spread created by excessive shallowness can reduce brightness or create undesirable patterns. Likewise, a very deep diamond may hide weight below the girdle. Read lab-grown diamond carat weight explained and carat weight versus visible diamond size.

A diamond's visual performance—its brightness, fire, and scintillation—depends heavily on its precision cut proportions.

Cut controls much of the brightness, fire, scintillation, contrast and pattern seen in normal wear. A diamond with strong light return can appear more lively than another with a higher colour or clarity grade but weaker proportions.

For eligible round brilliants, compare:

• overall cut grade or applicable quality assessment;
• table percentage;
• depth percentage;
• crown angle and height;
• pavilion angle and depth;
• girdle;
• culet;
• polish; and
• symmetry.

Do not select one isolated “ideal” number. Proportions interact. Two diamonds can both fall within broad acceptable ranges yet create different patterns.

For fancy shapes, examine outline and length-to-width preference, symmetry of wings, shoulders, lobes or corners, bow-tie strength in ovals, pears and marquises, dark or watery areas, edge-to-edge brightness, step-pattern balance in emerald and Asscher cuts, and protection requirements for points and corners.

Read lab-grown diamond cut explained.

If both reports use individual D–Z grades, first note the letter difference. Then ask whether that difference is visible in the chosen shape, size and metal.

Colour can appear more noticeable in larger diamonds, some step-cut and elongated shapes, white-metal settings, diamonds viewed from the side, and comparisons beside higher-colour side stones.

Yellow and rose-toned metals can harmonise with warmer grades. White prongs on a yellow band can create a different result from an entirely yellow setting.

Also inspect for undertones or colour distribution not fully communicated by one letter. Use neutral lighting and actual-stone imagery rather than photographs with different white balance.

If one report uses an overall GIA Premium or Standard classification, do not invent an exact colour grade. Compare the classification criteria, report and physical appearance as supplied. See lab-grown diamond colour grades explained.

Comparing inclusion position and contrast under magnification clarifies whether a diamond is visually clean.

Two VS2 diamonds can differ substantially. One might have a faint edge inclusion; another might contain a dark feature beneath the table.

Compare:

• the grade-setting inclusion;
• whether it is dark or transparent;
• its position;
• whether it is visible face-up without magnification;
• whether a cloud affects transparency;
• whether a feather reaches the surface; and
• whether the setting can protect a vulnerable area safely.

Use the clarity plot when available, but remember that it is a diagram rather than a scaled photograph. Compare the plot with the actual 360-degree video.

“Eye-clean” is not an official grade. Ask the seller to define viewing distance, lighting and direction. A diamond can be eye-clean face-up yet show an inclusion clearly from the side. See lab-grown diamond clarity grades explained.

Clarity grade and transparency are related but not identical buying questions. A diamond can have no large visible inclusion yet look subdued because of dense microscopic features, growth structures, poor cut, surface residue or photography.

Compare both diamonds under the same neutral conditions. Look for crisp facet edges, lively contrast during movement, a clear rather than milky appearance, consistent brightness across the face, and no unexplained haze.

Ask for confirmation that images show the actual stones and have not been subjected to different retouching. If one appears hazy, have a qualified professional determine whether the cause is internal, surface-related or photographic.

Polish: Polish describes facet-surface finish. Higher polish results generally reduce visible polishing features, although small differences between top categories may not be noticeable without magnification.

Symmetry: Symmetry describes facet alignment and geometric relationships. For fancy shapes, it also affects outline balance and the alignment of points, lobes and corners.

Fluorescence: Fluorescence is a diamond’s response to ultraviolet radiation. Compare its reported strength and colour, then examine whether it has any relevant effect under daylight or UV-rich conditions. It is not automatically negative.

When the two diamonds otherwise tie, finish and fluorescence can help explain a price or appearance difference.

If the report discloses CVD or HPHT growth, record it accurately. Neither method is automatically superior.

Review report comments for:

• CVD or HPHT growth;
• “as-grown” wording;
• evidence or absence of post-growth treatment;
• colour treatment comments; and
• any service-specific limitations.

Post-growth treatment may be used to alter colour. The material remains diamond, but treatment history should be disclosed and may matter to the buyer’s preferences. Do not reject a stone merely because it is CVD, HPHT or treated. Use the information as one field within the complete comparison. Read CVD vs HPHT lab-grown diamonds.

Video can reveal differences the report cannot, but only when the comparison conditions are fair.

Request the actual diamond (not a representative sample), neutral background, identical lighting, identical camera distance and exposure, face-up/side/rotating views, realistic scale plus magnification, no beauty filter or colour manipulation, and a side-by-side clip where possible.

Look for brightness across the entire face, balanced pattern, unwanted dark zones, transparency, inclusion visibility and shape symmetry.

Do not compare one diamond in a professional spotlight video with another in flat office light. The production difference can overwhelm the diamond difference.

Testing how a diamond outline fits a ring mounting ensures correct positioning and maximum safety.

The technically stronger loose diamond may not be the stronger choice for every design.

Consider whether the diamond fits the existing setting dimensions, whether points and corners can be protected, setting height and lifestyle, metal colour and colour perception, centre-to-side-stone matching, whether a prong would conceal the inscription, whether an edge inclusion sits near a required prong, and whether resizing or custom manufacture is included.

For earrings, matching between two principal diamonds matters as much as either stone in isolation. Compare dimensions, colour, clarity, fluorescence and face-up performance as a pair.

Only compare price after identity and visual suitability are established.

For similarly graded loose diamonds, price per carat can be calculated: Price ÷ carat weight = price per carat. This can help normalise slightly different weights, but it does not adjust for cut, dimensions, report, treatment, transparency or service. It should never become the sole decision rule.

Also compare VAT and duties, insured shipping, return period and conditions, resizing, setting cost, warranty, inspection and aftercare, production time, and whether the exact report and inscription are supplied.

A lower diamond price can become more expensive if necessary services are excluded.

Eliminate a diamond if: the report cannot be verified; origin or treatment disclosure is unclear; report and stone measurements do not match; the seller cannot provide actual-stone imagery; transparency appears materially compromised; an inclusion creates an unresolved durability concern; the cut produces an unattractive pattern; the diamond does not fit the intended setting; or return conditions do not permit reasonable inspection.

Use these tie-breakers when both pass: 1. More attractive real light performance; 2. Better face-up dimensions without sacrificing cut; 3. Less visible or safer inclusion placement; 4. More suitable colour for the setting; 5. Better shape outline and symmetry; 6. Clearer treatment and report documentation; 7. Better price for the complete service package.

This hierarchy keeps visible beauty and confidence ahead of microscopic paper differences.

Consider two hypothetical round lab-grown diamonds with IGI-style individual grades:

Diamond B has higher paper colour and clarity and slightly more weight. Diamond A has greater visible diameter, appears eye-clean and performs better in the supplied comparison video. If both reports verify and no durability issue exists, many appearance-led buyers could reasonably choose Diamond A.

The example does not establish universal thresholds. It demonstrates why the winner cannot be selected by reading only the highest grades.

An IGI loose lab-grown diamond report may provide individual carat, colour, clarity and cut results where applicable, plus polish, symmetry, fluorescence, measurements and comments.

GIA’s current qualifying colourless-to-near-colourless laboratory-grown quality assessment classifies the accepted diamond as Premium or Standard. It does not always provide the same individual grade fields.

When comparing across these systems:

1. Do not translate Premium into an invented D/VVS/Excellent listing.
2. Read the current published criteria for the GIA classification.
3. Compare measurable fields and the actual stones.
4. Preserve each laboratory’s exact wording.
5. Decide whether the missing individual detail affects the purchase.

For a direct paper comparison, two diamonds reported by the same laboratory under the same service are easier to normalise. Cross-system comparison remains possible, but it depends more heavily on physical inspection and seller transparency. Read how lab-grown diamonds are graded and what makes lab-grown diamonds different.

Avoid these common errors when comparing certified lab-grown diamonds:

• Choosing the highest grades automatically: Microscopic differences may cost more without improving visible appearance.
• Comparing reports without verifying them: A professional-looking PDF is not enough. Use the official laboratory database.
• Ignoring measurements: Carat alone does not reveal face-up size.
• Treating all Excellent cuts as identical: Proportions and real patterns can still differ within a broad grade.
• Comparing clarity letters without inclusion location: Position and contrast can matter more to the wearer than one grade step.
• Comparing videos shot differently: Lighting and exposure can create a false winner.
• Assuming CVD or HPHT determines quality: Evaluate the finished stone, report and treatment history.
• Comparing loose and finished prices: Separate diamond, setting, tax, delivery and service costs.
• Forgetting the return policy: Online imagery cannot fully replace real-life inspection.

When a customer compares principal diamonds for Aurelia Royale jewellery, the comparison should use the same field order and avoid hiding weaker specifications.

Each individually reported diamond should show its laboratory, report service, report number, origin, carat, measurements, colour, clarity, cut information, polish, symmetry, fluorescence, growth and treatment comments where supplied, and accurate video.

Pricing should state what is included. Settings should show metal type, fineness, centre-stone compatibility, accent-diamond details, production timing, return conditions and warranty.

If two stones use different report systems, Aurelia should explain the difference rather than converting terminology. For help with a specific comparison, contact Aurelia Royale.

• Are both reports verified officially?
• Do the inscriptions and physical specifications match?
• Are report services comparable?
• Have shape and setting already been chosen?
• Which diamond has better light performance?
• Which uses its weight more effectively?
• Is the colour difference visible in the intended metal?
• Where is each grade-setting inclusion?
• Are both diamonds transparent and eye-clean to the buyer’s standard?
• Do polish, symmetry and fluorescence differ?
• Are growth and treatment comments clear?
• Were videos captured under identical conditions?
• Does either stone create a setting or durability problem?
• What does each price include?
• Are returns, warranty and aftercare comparable?
• Which difference will the wearer actually notice?