How much does a 5.00ct+ I SI2 lab grown round diamond cost?

As of September 2026, 5.00ct+ I SI2 lab grown round diamonds typically cost £21,478 GBP to £91,438 GBP, with a median price of £53,120 GBP. There are currently 19 diamonds matching this specification available across retailers.

Where can I find the best price on a I SI2 round diamond?

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5.00ct+ I SI2 Lab Grown Round

Quick answer

As of September 2026, there are 19 lab grown round diamonds with I colour and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £21,478 GBP to £91,438 GBP, with a median of £53,120 GBP. At least 6 retailers stock this exact specification. Half of all listings fall between £4,822 GBP and £9,745 GBP per carat. The same specification in natural form lists at a median of about £12,654 GBP per carat.

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

5.01ct Round I SI2, GIA, score 63 of 100, from £61,748 GBP

Caratlytics Diamond Price Index, August 2026: natural diamonds at 2,184 USD per carat and lab-grown at 464 USD per carat, a natural to lab ratio of 4.7 to 1. Round lab grown stones in the index: 438 USD per carat, -14.1% month on month. See the full index release

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

Last updated: September 2026

Available

Lowest Price

£16,552 GBP

Highest Price

£124,772 GBP

Average Price

£55,515 GBP

Market Intelligence

Retailers Selling

Price Spread

77.5%

Price Range

Price per carat distribution across retailers

$8,069/ct

10th Percentile

$4,642

Median

$8,069

90th Percentile

$12,846

Score Distribution

19 diamonds scored across 2 quality tiers

Good

10 (52.6%)

Average

9 (47.4%)

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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