How much does a 0.50 to 0.74ct I SI2 natural marquise diamond cost?

As of October 2026, 0.50 to 0.74ct I SI2 natural marquise diamonds typically cost £355 GBP to £894 GBP, with a median price of £545 GBP. There are currently 164 diamonds matching this specification available across retailers.

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

About 29% of these diamonds are available at multiple retailers, with an average price spread of 39%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.50 to 0.74ct I SI2 Natural Marquise

Quick answer

As of October 2026, there are 164 natural marquise diamonds with I colour and SI2 clarity in the 0.50 to 0.74ct range available across retailers worldwide. Prices typically run £355 GBP to £894 GBP, with a median of £545 GBP. At least 53 retailers stock this exact specification, and 29% of the stones appear at more than one of them, with an average price spread of 39%. Half of all listings fall between £827 GBP and £1,219 GBP per carat. The same specification in lab grown form lists at a median of about £473 GBP per carat. Over the last 30 days the median price moved -1.3% and the number of listings moved +5.7%.

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. Marquise natural stones in the index: 2,268 USD per carat, +10.8% 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

164

Lowest Price

£264 GBP

Highest Price

£1,929 GBP

Average Price

£597 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

29.0%

Price Spread

39.1%

30-Day Price Trend

-1.3%

30-Day Supply Change

+5.7%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$1,343/ct

10th Percentile

$940

Median

$1,343

90th Percentile

$2,142

Score Distribution

423 diamonds scored across 4 quality tiers

Excellent

45 (10.6%)

Very Good

128 (30.3%)

Good

105 (24.8%)

Average

145 (34.3%)

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Consider Instead

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

J SI2J colour is visually identical to I to the naked eye

Save 10%

Lab-Grown I SI2Same specifications, lab-grown origin

Save 53%

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