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

As of November 2026, 1.00 to 1.49ct I SI1 natural heart diamonds typically cost £1,016 GBP to £3,154 GBP, with a median price of £1,748 GBP. There are currently 354 diamonds matching this specification available across retailers.

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

About 45% of these diamonds are available at multiple retailers, with an average price spread of 57%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.00 to 1.49ct I SI1 Natural Heart

Quick answer

As of November 2026, there are 354 natural heart diamonds with I colour and SI1 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run £1,016 GBP to £3,154 GBP, with a median of £1,748 GBP. At least 65 retailers stock this exact specification, and 45% of the stones appear at more than one of them, with an average price spread of 57%. Half of all listings fall between £1,240 GBP and £2,145 GBP per carat. The same specification in lab grown form lists at a median of about £601 GBP per carat. Over the last 30 days the median price moved -0.3% and the number of listings moved +13.4%.

Three of the best scored stones at this specification right now:

Caratlytics Diamond Price Index, October 2026: natural diamonds at 2,202 USD per carat and lab-grown at 462 USD per carat, a natural to lab ratio of 4.8 to 1. Heart natural stones in the index: 2,289 USD per carat, -3.7% 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: November 2026

Available

354

Lowest Price

£647 GBP

Highest Price

£6,437 GBP

Average Price

£1,924 GBP