How much does a 0.75 to 0.99ct I SI1 natural heart diamond cost?

As of October 2026, 0.75 to 0.99ct I SI1 natural heart diamonds typically cost £611 GBP to £1,856 GBP, with a median price of £933 GBP. There are currently 169 diamonds matching this specification available across retailers.

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

About 37% of these diamonds are available at multiple retailers, with an average price spread of 90%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.75 to 0.99ct I SI1 Natural Heart

Quick answer

As of October 2026, there are 169 natural heart diamonds with I colour and SI1 clarity in the 0.75 to 0.99ct range available across retailers worldwide. Prices typically run £611 GBP to £1,856 GBP, with a median of £933 GBP. At least 60 retailers stock this exact specification, and 37% of the stones appear at more than one of them, with an average price spread of 90%. Half of all listings fall between £953 GBP and £2,061 GBP per carat. Over the last 30 days the median price moved -1.8% and the number of listings moved +6.7%.

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. Heart natural stones in the index: 2,374 USD per carat, +9.8% 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

169

Lowest Price

£417 GBP

Highest Price

£4,608 GBP

Average Price

£1,112 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

36.8%

Price Spread

89.8%

30-Day Price Trend

-1.8%

30-Day Supply Change

+6.7%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$1,653/ct

10th Percentile

$1,080

Median

$1,653

90th Percentile

$3,484

Score Distribution

429 diamonds scored across 4 quality tiers

Excellent

68 (15.9%)

Very Good

65 (15.2%)

Good

142 (33.1%)

Average

154 (35.9%)

Find Your Diamond

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Related Specifications

D IF D VVS1 D VVS2 D VS1 D VS2 D SI1 E IF E VVS1 E VVS2 E VS1 E VS2 E SI1 F IF F VVS1 F VVS2 F VS1 F VS2 F SI1 G IF G VVS1 G VVS2 G VS1 G VS2 G SI1 H IF H VVS1 H VVS2 H VS1 H VS2 H SI1 I IF I VVS1 I VVS2 I VS1 I VS2 I SI1