How much does a 1.50 to 1.99ct I SI2 lab grown cushion diamond cost?

As of October 2026, 1.50 to 1.99ct I SI2 lab grown cushion diamonds typically cost £327 GBP to £5,558 GBP, with a median price of £492 GBP. There are currently 4 diamonds matching this specification available across retailers.

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

About 45% of these diamonds are available at multiple retailers, with an average price spread of 147%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI2 Lab Grown Cushion

Quick answer

As of October 2026, there are 4 lab grown cushion diamonds with I colour and SI2 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run £327 GBP to £5,558 GBP, with a median of £492 GBP. At least 23 retailers stock this exact specification, and 45% of the stones appear at more than one of them, with an average price spread of 147%. Half of all listings fall between £219 GBP and £819 GBP per carat. The same specification in natural form lists at a median of about £2,419 GBP per carat. Over the last 30 days the median price moved -4.9% and the number of listings moved +0.3%.

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

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. Cushion lab grown stones in the index: 516 USD per carat, +6.9% 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

£294 GBP

Highest Price

£6,158 GBP

Average Price

£2,470 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

44.8%

Price Spread

146.9%

30-Day Price Trend

-4.9%

30-Day Supply Change

+0.3%

Volatility (30d)

0.03

Price Range

Price per carat distribution across retailers

$544/ct

10th Percentile

$244

Median

$544

90th Percentile

$4,041

Score Distribution

7 diamonds scored across 3 quality tiers

Very Good

3 (42.9%)

Good

2 (28.6%)

Average

2 (28.6%)

Find Your Diamond

Search 4 I SI2 cushion diamonds and compare prices.

Search Diamonds

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