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

As of October 2026, 1.50 to 1.99ct I SI2 natural radiant diamonds typically cost £2,464 GBP to £6,875 GBP, with a median price of £4,416 GBP. There are currently 166 diamonds matching this specification available across retailers.

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

About 33% of these diamonds are available at multiple retailers, with an average price spread of 48%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI2 Natural Radiant

Quick answer

As of October 2026, there are 166 natural radiant diamonds with I colour and SI2 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run £2,464 GBP to £6,875 GBP, with a median of £4,416 GBP. At least 54 retailers stock this exact specification, and 33% of the stones appear at more than one of them, with an average price spread of 48%. Half of all listings fall between £2,188 GBP and £3,557 GBP per carat. The same specification in lab grown form lists at a median of about £700 GBP per carat. Over the last 30 days the median price moved -0.8% and the number of listings moved +16.4%.

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 natural stones in the index: 3,091 USD per carat, +13.2% 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

166

Lowest Price

£1,567 GBP

Highest Price

£12,625 GBP

Average Price

£4,579 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

33.2%

Price Spread

48.0%

30-Day Price Trend

-0.8%

30-Day Supply Change

+16.4%

Volatility (30d)

0.00

Price Range

Price per carat distribution across retailers

$3,802/ct

10th Percentile

$2,322

Median

$3,802

90th Percentile

$5,814

Score Distribution

499 diamonds scored across 4 quality tiers

Excellent

98 (19.6%)

Very Good

93 (18.6%)

Good

89 (17.8%)

Average

219 (43.9%)

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Consider Instead

Save money without compromising on what matters. These alternatives are visually similar but cost less.

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

Save 25%

Lab-Grown I SI2Same specifications, lab-grown origin

Save 75%

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