How much does a 5.00ct+ J SI2 lab grown cushion diamond cost?

As of September 2026, 5.00ct+ J SI2 lab grown cushion diamonds typically cost £38,704 GBP to £70,651 GBP, with a median price of £44,551 GBP. There are currently 7 diamonds matching this specification available across retailers.

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

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5.00ct+ J SI2 Lab Grown Cushion

Quick answer

As of September 2026, there are 7 lab grown cushion diamonds with J colour and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £38,704 GBP to £70,651 GBP, with a median of £44,551 GBP. At least 5 retailers stock this exact specification. Half of all listings fall between £8,383 GBP and £11,025 GBP per carat. The same specification in natural form lists at a median of about £10,619 GBP per carat.

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

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. Cushion lab grown stones in the index: 466 USD per carat, -14.7% 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

£38,631 GBP

Highest Price

£82,795 GBP

Average Price

£51,819 GBP

Market Intelligence

Retailers Selling

Price Spread

25.0%

Price Range

Price per carat distribution across retailers

$14,298/ct

10th Percentile

$10,420

Median

$14,298

90th Percentile

$15,245

Score Distribution

7 diamonds scored across 2 quality tiers

Good

3 (42.9%)

Average

4 (57.1%)

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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