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

As of October 2026, 1.50 to 1.99ct I SI2 lab grown radiant diamonds typically cost £960 GBP to £4,490 GBP, with a median price of £1,453 GBP. There are currently 4 diamonds matching this specification available across retailers.

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

About 45% of these diamonds are available at multiple retailers, with an average price spread of 84%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI2 Lab Grown Radiant

Quick answer

As of October 2026, there are 4 lab grown radiant diamonds with I colour and SI2 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run £960 GBP to £4,490 GBP, with a median of £1,453 GBP. At least 11 retailers stock this exact specification, and 45% of the stones appear at more than one of them, with an average price spread of 84%. Half of all listings fall between £653 GBP and £1,240 GBP per carat. The same specification in natural form lists at a median of about £2,873 GBP per carat. Over the last 30 days the median price moved +1.4% and the number of listings moved +7.1%.

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. Radiant lab grown stones in the index: 474 USD per carat, -2.1% 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

£837 GBP

Highest Price

£5,249 GBP

Average Price

£2,513 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

45.5%

Price Spread

83.8%

30-Day Price Trend

+1.4%

30-Day Supply Change

+7.1%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$932/ct

10th Percentile

$809

Median

$932

90th Percentile

$1,785

Score Distribution

5 diamonds scored across 3 quality tiers

Excellent

1 (20.0%)

Good

1 (20.0%)

Average

3 (60.0%)

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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