How much does a 5.00ct+ I SI2 natural round diamond cost?

As of September 2026, 5.00ct+ I SI2 natural round diamonds typically cost £25,413 GBP to £109,305 GBP, with a median price of £51,774 GBP. There are currently 340 diamonds matching this specification available across retailers.

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

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

5.00ct+ I SI2 Natural Round

Quick answer

As of September 2026, there are 340 natural round diamonds with I colour and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £25,413 GBP to £109,305 GBP, with a median of £51,774 GBP. At least 12 retailers stock this exact specification. Half of all listings fall between £8,843 GBP and £15,195 GBP per carat. The same specification in lab grown form lists at a median of about £5,973 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

340

Lowest Price

£13,222 GBP

Highest Price

£650,216 GBP

Average Price

£63,393 GBP