How much does a 1.50 to 1.99ct G SI1 lab grown cushion diamond cost?

As of October 2026, 1.50 to 1.99ct G SI1 lab grown cushion diamonds typically cost £268 GBP to £926 GBP, with a median price of £495 GBP. There are currently 41 diamonds matching this specification available across retailers.

Where can I find the best price on a G SI1 cushion diamond?

About 26% of these diamonds are available at multiple retailers, with an average price spread of 79%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct G SI1 Lab Grown Cushion

Quick answer

As of October 2026, there are 41 lab grown cushion diamonds with G colour and SI1 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run £268 GBP to £926 GBP, with a median of £495 GBP. At least 36 retailers stock this exact specification, and 26% of the stones appear at more than one of them, with an average price spread of 79%. Half of all listings fall between £227 GBP and £504 GBP per carat. The same specification in natural form lists at a median of about £3,534 GBP per carat. Over the last 30 days the median price moved +8.2% and the number of listings moved +3.8%.

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

£147 GBP

Highest Price

£2,306 GBP

Average Price

£572 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

26.0%

Price Spread

78.9%

30-Day Price Trend

+8.2%

30-Day Supply Change

+3.8%

Volatility (30d)

0.03

Price Range

Price per carat distribution across retailers

$471/ct

10th Percentile

$216

Median

$471

90th Percentile

$893

Score Distribution

128 diamonds scored across 4 quality tiers

Excellent

16 (12.5%)

Very Good

27 (21.1%)

Good

27 (21.1%)

Average

58 (45.3%)

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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