How much does a 6-carat lab-grown diamond cost?

In our September 2026 comparison, a loose six-carat lab-grown diamond cost $1,711 to $8,790. Ritani was the least expensive and Brilliant Earth the most expensive. The seller-balanced typical price was $5,340.

We compared round diamonds from 5.95 to 6.05 carats, with E color, VVS2 clarity, and a high cut grade. The setting is extra and may need to be custom-made for a stone this large.

Ritani's five lowest qualifying round stones cost $1,661 to $1,720, with a median of $1,711. We count each seller once rather than averaging hundreds of low-cost listings into the market figure.

Read our Ritani review See six-carat diamonds at Ritani

Six-carat lab-grown diamond prices in 2026

Prices checked September 3, 202653 sampled listings across the full price study
Lowest seller benchmark$1,711
Typical across sellers$5,340
Full seller range$1,711–$8,790

“Typical” is the median of the seller benchmark prices above. Each seller counts once, so a jeweler with a much larger inventory cannot pull the figure down simply by listing more diamonds.

Seller and samplePriceDifference
RitaniMedian of five lowest results from the authorized API sample$1,711Lowest in our test
With Clarity6.00 ct current E/VVS2 Excellent-cut result$5,001192.3% more
Grown Brilliance6.00 ct current IGI Ideal-cut result$5,340212.1% more
Blue Nile6.00 ct current IGI Excellent-cut result$7,994367.2% more
Brilliant EarthMedian of five lowest close feed results; grading lab not supplied$8,790413.7% more

The high and low benchmarks differ by more than $7,000. That can reflect retailer overhead, service, settings, and the available inventory as well as the individual stone. At this size, compare more than the price: inspection quality and return terms matter because imperfections are easier to see.

How big is a six-carat diamond?

A well-proportioned six-carat round diamond is roughly 11.7 millimeters across. It is a statement size on almost any hand. Ovals, marquises, pears, and emerald cuts can extend even farther across the finger.

The guide was right to treat this as a jewelry-design question as well as a price question. A very high basket can snag and tip; an ultra-thin band can spin. We would favor a low, supportive gallery, strong prongs, and a band with enough width to balance the stone.

How to choose a six-carat diamond

Prioritize cut over the round-number milestone. A deep stone may hide weight underneath and look smaller from the top. Use the video to check brightness and contrast, then compare length, width, depth, table, symmetry, polish, and fluorescence on the report.

You may not need E/VVS2. G–H color and eye-clean VS clarity can save thousands, but large diamonds reveal more. Inspect for visible tint, inclusions, haziness, strain, and growth marks. Step cuts often need more clarity; brilliant cuts hide inclusions more effectively.

Search below six carats. A well-cut 5.75- to 5.99-carat diamond can look nearly identical. Also confirm the exact stone dimensions with the setting maker and read the return terms before custom work begins.

Six-carat round versus fancy-shaped diamonds

Fancy shapes can offer excellent value. Elongated ovals, pears, marquises, and emerald cuts often look larger than a six-carat round diamond. Some shapes cost less, but the price changes with demand, proportions, and how efficiently each stone was cut.

To compare shapes without mixing in different seller markups, we used the five lowest qualifying Ritani API results for each available shape. Every diamond was 5.95 to 6.05 carats, E color, VVS2 clarity, and IGI graded. Round diamonds had Ritani's Ideal label; the fancy shapes had Very Good or better cut labels. In total, 648 Ritani diamonds met those rules across nine shapes. No Asscher diamond qualified on the check date.

Fancy-shaped price comparisonPrices from Ritani, using up to five qualifying diamonds per shape
ShapeMedian priceSample rangeCut used
Round$1,711$1,661–$1,720Ideal
Oval$1,992$1,992–$1,993Very Good
Emerald$1,985$1,978–$1,988Very Good
Pear$2,045$1,727–$2,057Very Good
Marquise$2,247$2,127–$2,521Very Good
Radiant$2,129$2,086–$2,193Very Good
Cushion$2,280$2,095–$2,350Very Good
Princess$2,010$1,789–$2,317Very Good
Heart$2,340$2,340–$2,363Very Good

Round had the lowest five-listing median at $1,711. Heart was highest at $2,340. The absence of an Asscher row is useful information rather than a data gap to hide: inventory becomes thinner and less even at six carats.

Current six-carat examples

Round lab-grown diamond shown face-up

round · IGI

$1,661

6.00 ct · E · VVS2 · Ideal

Lowest qualifying round result in the API capture.

Visit Ritani
Oval lab-grown diamond shown face-up

oval · IGI

$1,992

6.05 ct · E · VVS2 · Very Good

Lowest qualifying oval result in the API capture.

Visit Ritani
Emerald-cut lab-grown diamond shown face-up

emerald · IGI

$1,978

6.01 ct · E · VVS2 · Very Good

Lowest qualifying emerald result in the API capture.

Visit Ritani
Pear-shaped lab-grown diamond shown face-up

pear · IGI

$1,727

6.00 ct · E · VVS2 · Very Good

Lowest qualifying pear result in the API capture.

Visit Ritani

Ritani's catalog images show each diamond shape, not the exact stones in our sample. Listings and prices can change after our check, so confirm the current diamond on the seller's site.

Treat these as price examples, not automatic recommendations. Inspect the exact video, outline, measurements, and grading report before buying.

What setting works for a six-carat diamond?

A solitaire keeps the ring wearable and lets the stone lead. A hidden halo adds detail beneath the center without adding much face-up width. A three-stone or full halo design can become extremely broad, so try a comparable size in person before choosing one.

A bezel offers protection but adds visual weight. A cathedral setting can support the center, although it may sit higher. Whatever the style, ask how the head is attached, how many prongs secure the stone, and whether the ring can be resized later.

Where should you buy a six-carat diamond?

Prices can vary widely within the same carat range. Compare the actual diamond, grading report and complete ring price—not only the headline price—before choosing a seller.

JewelerBest forOur ratingShop
RitaniPrices, loose-diamond selection and value4.7/5See at Ritani
Grown BrillianceFinished jewelry and distinctive ring designs4.5/5See at Grown Brilliance
Blue NileA polished all-round shopping experience4.6/5See at Blue Nile
Brilliant EarthPremium settings, showrooms and guided shopping4.5/5See at Brilliant Earth

Ritani: best for price and inventory

Ritani had the lowest current benchmark and 648 diamonds met our rules across nine shapes. Its deep inventory and transparent cost breakdown make it the first place we would search.

Grown Brilliance: best for design-led rings

Grown Brilliance's benchmark sat below Blue Nile and Brilliant Earth, and its strength is finished jewelry. It is worth checking when the setting matters as much as the loose stone.

Blue Nile: best all-round shopping experience

Blue Nile offers strong inspection tools, support, showrooms, and an established ring builder. It also carries the James Allen collection now that James Allen is no longer a standalone store.

Brilliant Earth: best for showrooms and labeled sustainability options

Brilliant Earth was the most expensive benchmark but offers a large showroom network, distinctive settings, and specifically labeled Renewable, Capture, and Sustainably Rated collections.

Is a six-carat lab-grown diamond worth it?

Only if you truly want the size and expect to wear it. Lab-grown makes an unusually large diamond financially accessible, but the ring needs more design care and the resale market is weak.

Buy it for the appearance, not as an investment. New lab-grown prices have fallen sharply and may continue to do so. If sustainability matters, ask for specific evidence about energy, carbon, metal, and manufacturing rather than relying on the word “lab-grown” alone.

How six-carat prices have changed

Our October 2024 research found round six-carat prices from $5,655 to $34,990 across five sellers. Those figures used I–J color and VS1–VS2 clarity and reported seller ranges. The current E/VVS2 benchmark is narrower, so the older figures are valuable history but not a formal index.

October 2024 archive

$5,655–$34,990

5 sellers · Round diamonds near six carats, I–J color, VS1–VS2 clarity, and Excellent or Ideal cut; seller ranges rather than one shared aggregation.

September 2026 test

$1,711–$8,790

5 sellers · Round diamonds from 5.95 to 6.05 carats, E color, VVS2 clarity, and a high cut grade; IGI grading where the source exposed it.

The dated and current ranges show how dramatically prices have moved, but they are not a like-for-like index: the studies used different color and clarity grades and reported seller ranges.

See our october 2024 fancy-shape archive

Starting prices near six carats, I–J color, VS1–VS2 clarity, and Very Good or better seller-reported cut. Individual listings are no longer current.

Sellerovalemeraldpearprincessradiantcushionheart
Ritani$5,623$4,151$6,619$4,987$5,904$5,236$13,294
Grown Brilliance$5,880$5,585$7,585$10,395$6,500$5,880$18,850
Brilliant Earth$14,140$11,860$14,410$14,490$10,150$17,270$16,630
James Allen (historical)$19,290$16,450$18,680$17,060$25,840$26,280—

Our verdict

Close six-carat lab-grown diamonds cost $1,711 to $8,790 in our current comparison. The seller-balanced typical price was $5,340. Start at Ritani for price, compare With Clarity and Grown Brilliance for middle-ground options, and use Blue Nile or Brilliant Earth when their showrooms and buying experience are worth more to you.

At this size, spend more time on the actual stone and setting than on the certificate headline. Cut, visible dimensions, comfort, security, and return terms are the details that decide whether the ring works.

How we researched six-carat prices

We checked US listings on September 3, 2026. The target was 5.95–6.05 carats, E color, VVS2 clarity, and a high cut grade. Ritani's complete filtered API capture produced 648 qualifying offers across nine shapes; no qualifying Asscher result was available. Brilliant Earth's feed supplied 47 close high-cut round results but does not expose the grading lab. With Clarity, Grown Brilliance, and Blue Nile contributed current E/VVS2 public matches.

The current shape table compares shapes within Ritani, so different seller markups do not distort the result. Asscher is omitted because the API sample did not contain a qualifying result.

For the seller-balanced typical price, we take the median of the seller benchmark prices. Each seller contributes one benchmark, regardless of inventory size.

Prices checkedSeptember 3, 2026MarketUnited StatesCurrencyUS dollarsBenchmark5.95–6.05 ct · E · VVS2 · IGI

Ritani's complete filtered API capture produced 648 qualifying diamonds across nine shapes. Brilliant Earth's feed supplied 47 close high-cut round results but no grading-lab field. With Clarity, Grown Brilliance, and Blue Nile use close current E/VVS2 public listings. Each seller contributes one benchmark to the typical price.

We kept the October 2024 seller and fancy-shape research as a dated archive. The current shape comparison uses one seller so that seller markup does not obscure shape inventory and price.

Compare other carat weights

Update history

This guide was first published in March 2024. The September 2026 edition adds current seller and API-backed shape comparisons, more practical setting and inspection advice, current examples, and historical price context while removing James Allen as a standalone shopping destination.