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

As of October 2026, 5.00ct+ I SI2 lab grown round diamonds typically cost £40,267 GBP to £58,387 GBP, with a median price of £57,826 GBP. There are currently 1 diamonds matching this specification available across retailers.

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

About 78% of these diamonds are available at multiple retailers, with an average price spread of 19%. A comparison tool like Carat Hunter lets you see all the prices side by side.

5.00ct+ I SI2 Lab Grown Round

Quick answer

As of October 2026, there are 1 lab grown round diamonds with I colour and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £40,267 GBP to £58,387 GBP, with a median of £57,826 GBP. At least 7 retailers stock this exact specification, and 78% of the stones appear at more than one of them, with an average price spread of 19%. Half of all listings fall between £7,133 GBP and £8,611 GBP per carat. The same specification in natural form lists at a median of about £10,457 GBP per carat. Over the last 30 days the median price moved -12.7% and the number of listings moved -27.7%.

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

5.01ct Round I SI2, GIA, grade C, from £58,527 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. Round lab grown stones in the index: 414 USD per carat, -5.0% 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

£35,877 GBP

Highest Price

£60,483 GBP

Average Price

£50,743 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

77.8%

Price Spread

18.8%

30-Day Price Trend

-12.7%

30-Day Supply Change

-27.7%

Volatility (30d)

0.10

Price Range

Price per carat distribution across retailers

$10,549/ct

10th Percentile

$1,584

Median

$10,549

90th Percentile

$13,912

Score Distribution

3 diamonds scored across 1 quality tiers

Average

3 (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