How much does a 0.75 to 0.99ct I SI2 natural round diamond cost?

As of October 2026, 0.75 to 0.99ct I SI2 natural round diamonds typically cost £639 GBP to £1,859 GBP, with a median price of £1,028 GBP. There are currently 948 diamonds matching this specification available across retailers.

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

About 36% of these diamonds are available at multiple retailers, with an average price spread of 59%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.75 to 0.99ct I SI2 Natural Round

Quick answer

As of October 2026, there are 948 natural round diamonds with I colour and SI2 clarity in the 0.75 to 0.99ct range available across retailers worldwide. Prices typically run £639 GBP to £1,859 GBP, with a median of £1,028 GBP. At least 58 retailers stock this exact specification, and 36% of the stones appear at more than one of them, with an average price spread of 59%. Half of all listings fall between £1,023 GBP and £1,778 GBP per carat. The same specification in lab grown form lists at a median of about £751 GBP per carat. Over the last 30 days the median price moved -1.4% and the number of listings moved +5.5%.

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. Round natural stones in the index: 2,248 USD per carat, +7.6% 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

948

Lowest Price

£296 GBP

Highest Price

£4,187 GBP

Average Price

£1,159 GBP