How much does a 4-carat lab-grown diamond cost?
In our September 2026 comparison, a loose four-carat lab-grown diamond cost $1,246 to $6,388. Ritani was the least expensive seller, while Blue Nile had the highest close benchmark. The seller-balanced typical price was $3,605.
We looked for round diamonds from 3.95 to 4.05 carats, with E color, VVS2 clarity, and a high cut grade. These prices exclude the setting, taxes, and optional protection plan.
The unusually low Ritani price is real in its current authorized catalog: its five lowest qualifying round diamonds had a median of $1,246. We count each seller once so that Ritani's large inventory does not pull a market-wide average down.
Read our Ritani review See four-carat diamonds at Ritani
Four-carat lab-grown diamond prices in 2026
“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 sample | Price | Difference |
|---|---|---|
| RitaniMedian of five lowest results from the authorized API sample | $1,246 | Lowest in our test |
| With Clarity4.00 ct current E/VVS2 Excellent-cut sale price | $3,067 | 146.1% more |
| Grown Brilliance4.01 ct current E/VVS2 Excellent-cut result | $3,605 | 189.3% more |
| Brilliant EarthMedian of five lowest close feed results; grading lab not supplied | $5,700 | 357.5% more |
| Blue Nile4.00 ct current GIA Excellent-cut result | $6,388 | 412.7% more |
The gap is more than $5,000 for broadly similar headline grades. Some buyers will value Blue Nile's showrooms, support, inspection tools, or ring builder. Those services can be worthwhile, but they do not make price comparison any less important.
What does a four-carat diamond look like?
A well-proportioned four-carat round diamond is roughly 10.2 millimeters across. It has a very large face-up presence and will dominate most engagement-ring settings. An oval, pear, marquise, or emerald cut can look even larger because the stone stretches farther along the finger.
At this size, comfort and security matter. A low basket, sturdy prongs, and a band wide enough to balance the stone can make the ring easier to wear. Very thin bands may look elegant in photographs but can spin or feel top-heavy.
Buying a four-carat diamond well
Cut should come before the exact milestone. A large poorly cut diamond can show obvious darkness, weak sparkle, or excess weight hidden in the depth. Compare the video, proportions, and millimeter dimensions—not merely the carat number.
E/VVS2 keeps our price test consistent, but many buyers can save with G–H color and eye-clean VS1–VS2 clarity. Four carats is large enough that tint and inclusions may be easier to spot, so inspect the individual stone carefully. Emerald and Asscher cuts are especially revealing because their broad facets make inclusions more visible.
Search below four carats. A well-cut 3.85- to 3.99-carat diamond can look virtually the same while avoiding a milestone premium. Then compare the complete ring totals and return rules before customizing or engraving.
Four-carat round versus fancy-shaped diamonds
Fancy shapes can offer excellent value. Elongated ovals, pears, marquises, and emerald cuts often look larger than a four-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 of ten shapes. Every diamond was 3.95 to 4.05 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, 2,539 Ritani diamonds met those rules.
| Shape | Median price | Sample range | Cut used |
|---|---|---|---|
| Round | $1,246 | $1,161–$1,251 | Ideal |
| Oval | $1,259 | $1,249–$1,259 | Very Good |
| Emerald | $1,337 | $1,308–$1,346 | Very Good |
| Pear | $1,171 | $1,171–$1,174 | Very Good |
| Marquise | $1,269 | $1,259–$1,269 | Very Good |
| Radiant | $1,085 | $1,074–$1,085 | Very Good |
| Cushion | $1,362 | $1,349–$1,390 | Very Good |
| Princess | $1,081 | $1,043–$1,087 | Very Good |
| Asscher | $1,531 | $1,374–$1,630 | Very Good |
| Heart | $1,337 | $1,114–$1,384 | Very Good |
Princess had the lowest five-listing median at $1,081; Asscher was highest at $1,531. The spread within one seller is much smaller than the spread between sellers. Shape should therefore be a design choice first, not a prediction about which inventory will always be cheapest.
Current four-carat examples
round · IGI
$1,161
4.00 ct · E · VVS2 · Ideal
Lowest qualifying round result in the API capture.
Visit Ritani
oval · IGI
$1,249
3.96 ct · E · VVS2 · Very Good
Lowest qualifying oval result in the API capture.
Visit Ritani
emerald · IGI
$1,308
4.02 ct · E · VVS2 · Very Good
Lowest qualifying emerald result in the API capture.
Visit Ritani
pear · IGI
$1,171
3.95 ct · E · VVS2 · Very Good
Lowest qualifying pear result in the API capture.
Visit RitaniRitani'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.
For elongated shapes, look for a pleasing outline and manageable bow tie. For step cuts, check that the center does not go dark or look transparent. At four carats, these details are easy to see from normal distance.
Ring styles that work at four carats
The guide featured several engagement-ring designs. A solitaire is still the cleanest way to let a stone this large lead. Hidden halos and small accent diamonds add detail without making the face-up outline much wider. A three-stone setting is possible, but it creates a very broad ring and needs careful proportioning.
We would choose a secure basket and try the ring on before committing if possible. Also check whether resizing, customization, or a special-order setting changes the return policy.
Where should you buy a four-carat diamond?
Ritani: best for price
Ritani was dramatically less expensive and offered thousands of qualifying stones. Its filters and cost transparency make it the best place to start.
Read our Ritani review Visit Ritani
Blue Nile: best all-round alternative
Blue Nile's benchmark was much higher, but it offers detailed videos, support, showrooms, and a polished ring builder. Its inventory now includes the James Allen collection.
Read our Blue Nile review Visit Blue Nile
Grown Brilliance: best for distinctive settings
Grown Brilliance is one of our preferred sellers for finished jewelry and design-led engagement rings. We have bought and returned several pieces and found the finish, packaging, and service strong.
Read our Grown Brilliance review Visit Grown Brilliance
Brilliant Earth: best for showrooms and labeled sustainability options
Brilliant Earth is worth comparing if you value its showrooms, ring designs, or Renewable, Capture, and Sustainably Rated lab-diamond collections.
Read our Brilliant Earth review Visit Brilliant Earth
Is a four-carat lab-grown diamond worth it?
It can be, if you want a genuinely large diamond and will enjoy wearing it. A comparable mined diamond can cost far more. The practical compromises are the ring's scale, weaker resale market, and the need to inspect a large stone carefully.
Do not treat it as an investment. Lab-grown prices have fallen and could fall further. Environmental claims also vary by producer, so look for concrete product-level evidence rather than assuming every lab-grown diamond has the same footprint.
How four-carat prices have changed
Our October 2024 research found round four-carat lab-grown diamond prices from $3,483 to $21,290 across six sellers. It used I–J color and VS1–VS2 clarity and seller price ranges. The current benchmark is narrower and higher grade, so this is historical context rather than a like-for-like index.
October 2024 archive
$3,483–$21,290
6 sellers · Round diamonds near four carats, I–J color, VS1–VS2 clarity, and Excellent or Ideal cut; seller ranges rather than one shared aggregation.
September 2026 test
$1,246–$6,388
5 sellers · Round diamonds from 3.95 to 4.05 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 four carats, I–J color, VS1–VS2 clarity, and Very Good or better seller-reported cut. Individual listings are no longer current.
| Seller | oval | emerald | pear | princess | radiant | cushion | heart |
|---|---|---|---|---|---|---|---|
| Ritani | $3,364 | $2,960 | $3,196 | $3,719 | $3,187 | $3,651 | $5,109 |
| Clean Origin | $3,508 | $2,879 | $4,594 | $2,912 | $2,937 | $2,597 | $7,741 |
| With Clarity | $3,686 | $3,208 | — | $3,295 | $3,405 | $3,305 | — |
| Grown Brilliance | $4,685 | $6,225 | $8,325 | $5,205 | $4,060 | $5,570 | — |
| Brilliant Earth | $7,690 | $8,010 | $6,670 | $7,190 | $8,080 | $7,820 | $10,180 |
| James Allen (historical) | $13,680 | $5,980 | $13,030 | $7,320 | $16,270 | $9,640 | $15,650 |
Our verdict
Close four-carat lab-grown diamonds cost $1,246 to $6,388 in our September 2026 test, with a seller-balanced typical price of $3,605. Ritani is the clear place to start on price. With Clarity offers a useful middle-ground comparison, while Grown Brilliance deserves a look for the setting itself.
How we researched four-carat prices
We checked US listings on September 3, 2026. The target was 3.95–4.05 carats, E color, VVS2 clarity, and a high cut grade. Ritani's complete filtered API capture produced 2,539 qualifying offers across ten shapes. Brilliant Earth's feed supplied 145 close high-cut round results but does not expose the grading lab. With Clarity and Grown Brilliance contributed current E/VVS2 public matches; Blue Nile contributed a current four-carat GIA Excellent-cut result.
The current shape table compares shapes within Ritani, so different seller markups do not distort the result. Each seller contributes one benchmark to the seller-balanced typical price.
For the seller-balanced typical price, we take the median of the seller benchmark prices. Each seller contributes one benchmark, regardless of inventory size.
Ritani's complete filtered API capture produced 2,539 qualifying diamonds across ten shapes. Brilliant Earth's feed supplied 145 close high-cut round results, but no grading-lab field. With Clarity and Grown Brilliance contributed current E/VVS2 public matches. Blue Nile's result was a current close public GIA-graded diamond. We use the median of seller benchmarks to prevent one large, inexpensive feed from distorting the typical price.
The October 2024 seller and shape tables remain as a dated archive. Current seller and shape comparisons are separate: one compares places to buy, while the other holds the seller constant.
Compare other carat weights
- 0.5-carat lab-grown diamond prices
- 0.75-carat lab-grown diamond prices
- 1-carat lab-grown diamond prices
- 1.5-carat lab-grown diamond prices
- 2-carat lab-grown diamond prices
- 3-carat lab-grown diamond prices
- 5-carat lab-grown diamond prices
- 6-carat lab-grown diamond prices
Update history
This guide was first published in March 2024. The September 2026 edition adds current seller and API-backed shape comparisons, restores the useful large-ring example and practical buying advice, keeps the historical tables as history, and removes James Allen as a standalone shopping option.