How much does a 3.00 to 4.99ct I SI2 natural round diamond cost?

As of September 2026, 3.00 to 4.99ct I SI2 natural round diamonds typically cost £9,931 GBP to £36,776 GBP, with a median price of £19,559 GBP. There are currently 1,277 diamonds matching this specification available across retailers.

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

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3.00 to 4.99ct I SI2 Natural Round

Quick answer

As of September 2026, there are 1,277 natural round diamonds with I colour and SI2 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run £9,931 GBP to £36,776 GBP, with a median of £19,559 GBP. At least 47 retailers stock this exact specification. Half of all listings fall between £4,762 GBP and £8,325 GBP per carat. The same specification in lab grown form lists at a median of about £6,965 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. Round natural stones in the index: 2,094 USD per carat, -3.8% 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

1,277

Lowest Price

£5,962 GBP

Highest Price

£85,006 GBP

Average Price

£21,473 GBP

Market Intelligence

Retailers Selling

Price Spread

52.8%

Price Range

Price per carat distribution across retailers

$9,123/ct

10th Percentile

$5,156

Median

$9,123

90th Percentile

$13,095

Score Distribution

1.3K diamonds scored across 4 quality tiers

Excellent

368 (28.8%)

Very Good

443 (34.7%)

Good

309 (24.2%)

Average

157 (12.3%)

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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