How much does a 5.00ct+ I SI1 natural radiant diamond cost?

As of September 2026, 5.00ct+ I SI1 natural radiant diamonds typically cost £42,382 GBP to £190,186 GBP, with a median price of £72,939 GBP. There are currently 58 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.

5.00ct+ I SI1 Natural Radiant

Quick answer

As of September 2026, there are 58 natural radiant diamonds with I colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £42,382 GBP to £190,186 GBP, with a median of £72,939 GBP. At least 6 retailers stock this exact specification. Half of all listings fall between £14,093 GBP and £21,726 GBP per carat. The same specification in lab grown form lists at a median of about £349 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

Lowest Price

£21,152 GBP

Highest Price

£506,551 GBP

Average Price

£107,709 GBP