How much does a 3.00 to 4.99ct J SI1 lab grown radiant diamond cost?

As of October 2026, 3.00 to 4.99ct J SI1 lab grown radiant diamonds typically cost £1,270 GBP to £1,935 GBP, with a median price of £1,603 GBP. There are currently 1 diamonds matching this specification available across retailers.

Where can I find the best price on a J SI1 radiant diamond?

About 44% of these diamonds are available at multiple retailers, with an average price spread of 87%. A comparison tool like Carat Hunter lets you see all the prices side by side.

3.00 to 4.99ct J SI1 Lab Grown Radiant

Quick answer

As of October 2026, there are 1 lab grown radiant diamonds with J colour and SI1 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run £1,270 GBP to £1,935 GBP, with a median of £1,603 GBP. At least 16 retailers stock this exact specification, and 44% of the stones appear at more than one of them, with an average price spread of 87%. Half of all listings fall between £428 GBP and £1,148 GBP per carat. The same specification in natural form lists at a median of about £5,444 GBP per carat.

Three of the best scored stones at this specification right now:

3.00ct Radiant J SI1, IGI, grade B+, from £1,187 GBP

Caratlytics Diamond Price Index, September 2026: natural diamonds at 2,335 USD per carat and lab-grown at 443 USD per carat, a natural to lab ratio of 5.3 to 1. Radiant lab grown stones in the index: 474 USD per carat, -2.1% month on month. See the full index release

Figures come from current listings across more than 100 retailers and refresh daily. The index is a monthly release.

Last updated: October 2026

Available

Lowest Price

£1,187 GBP

Highest Price

£2,018 GBP

Average Price

£1,603 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

44.4%

Price Spread

86.9%

Price Range

Price per carat distribution across retailers

$1,110/ct

10th Percentile

$468

Median

$1,110

90th Percentile

$2,096

Score Distribution

2 diamonds scored across 1 quality tiers

Very Good

2 (100.0%)

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Related Specifications

D IF D VVS1 D VVS2 D VS1 D VS2 D SI1 E IF E VVS1 E VVS2 E VS1 E VS2 E SI1 F IF F VVS1 F VVS2 F VS1 F VS2 F SI1 G IF G VVS1 G VVS2 G VS1 G VS2 G SI1 H IF H VVS1 H VVS2 H VS1 H VS2 H SI1 I IF I VVS1 I VVS2 I VS1 I VS2 I SI1