How much does a 1.00 to 1.49ct I SI2 lab grown cushion diamond cost?

As of September 2026, 1.00 to 1.49ct I SI2 lab grown cushion diamonds typically cost £1,066 GBP to £3,280 GBP, with a median price of £1,596 GBP. There are currently 30 diamonds matching this specification available across retailers.

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

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1.00 to 1.49ct I SI2 Lab Grown Cushion

Quick answer

As of September 2026, there are 30 lab grown cushion diamonds with I colour and SI2 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run £1,066 GBP to £3,280 GBP, with a median of £1,596 GBP. At least 4 retailers stock this exact specification. Half of all listings fall between £1,347 GBP and £2,726 GBP per carat. The same specification in natural form lists at a median of about £1,860 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

£183 GBP

Highest Price

£4,008 GBP

Average Price

£1,912 GBP

Market Intelligence

Retailers Selling

Price Spread

89.5%

Price Range

Price per carat distribution across retailers

$1,956/ct

10th Percentile

$1,671

Median

$1,956

90th Percentile

$4,317

Score Distribution

30 diamonds scored across 3 quality tiers

Very Good

1 (3.3%)

Good

5 (16.7%)

Average

24 (80.0%)

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J SI2J colour is visually identical to I to the naked eye

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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