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

As of October 2026, 0.75 to 0.99ct I SI1 natural princess diamonds typically cost £575 GBP to £1,620 GBP, with a median price of £899 GBP. There are currently 145 diamonds matching this specification available across retailers.

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

About 35% of these diamonds are available at multiple retailers, with an average price spread of 65%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.75 to 0.99ct I SI1 Natural Princess

Quick answer

As of October 2026, there are 145 natural princess diamonds with I colour and SI1 clarity in the 0.75 to 0.99ct range available across retailers worldwide. Prices typically run £575 GBP to £1,620 GBP, with a median of £899 GBP. At least 61 retailers stock this exact specification, and 35% of the stones appear at more than one of them, with an average price spread of 65%. Half of all listings fall between £836 GBP and £1,524 GBP per carat. The same specification in lab grown form lists at a median of about £1,204 GBP per carat. Over the last 30 days the median price moved -8.9% and the number of listings moved +14.4%.

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. Princess natural stones in the index: 2,158 USD per carat, +5.7% 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: October 2026

Available

145

Lowest Price

£427 GBP

Highest Price

£3,497 GBP

Average Price

£1,028 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

34.6%

Price Spread

65.2%

30-Day Price Trend

-8.9%

30-Day Supply Change

+14.4%

Volatility (30d)

0.02

Price Range

Price per carat distribution across retailers

$1,405/ct

10th Percentile

$984

Median

$1,405

90th Percentile

$2,989

Score Distribution

370 diamonds scored across 4 quality tiers

Excellent

59 (15.9%)

Very Good

63 (17.0%)

Good

102 (27.6%)

Average

146 (39.5%)

Find Your Diamond

Search 145 I SI1 princess diamonds and compare prices.

Search Diamonds

Consider Instead

Save money without compromising on what matters. These alternatives are visually similar but cost less.

J SI1J colour is visually identical to I to the naked eye

Save 15%

I SI2SI2 inclusions are not visible without magnification

Save 8%

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