How much does a 1.00 to 1.49ct I SI1 natural radiant diamond cost?

As of September 2026, 1.00 to 1.49ct I SI1 natural radiant diamonds typically cost £1,138 GBP to £3,183 GBP, with a median price of £1,769 GBP. There are currently 803 diamonds matching this specification available across retailers.

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

Compare prices across retailers on Carat Hunter to see all your options.

1.00 to 1.49ct I SI1 Natural Radiant

Quick answer

As of September 2026, there are 803 natural radiant diamonds with I colour and SI1 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run £1,138 GBP to £3,183 GBP, with a median of £1,769 GBP. At least 58 retailers stock this exact specification. Half of all listings fall between £1,437 GBP and £2,195 GBP per carat. The same specification in lab grown form lists at a median of about £1,032 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. Radiant natural stones in the index: 2,765 USD per carat, +6.0% 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

803

Lowest Price

£668 GBP

Highest Price

£5,690 GBP

Average Price

£1,971 GBP