How much does a 1.00 to 1.49ct I SI2 natural marquise diamond cost?

As of September 2026, 1.00 to 1.49ct I SI2 natural marquise diamonds typically cost £1,121 GBP to £3,599 GBP, with a median price of £2,008 GBP. There are currently 1,069 diamonds matching this specification available across retailers.

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

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1.00 to 1.49ct I SI2 Natural Marquise

Quick answer

As of September 2026, there are 1,069 natural marquise diamonds with I colour and SI2 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run £1,121 GBP to £3,599 GBP, with a median of £2,008 GBP. At least 52 retailers stock this exact specification. Half of all listings fall between £1,627 GBP and £2,582 GBP per carat. The same specification in lab grown form lists at a median of about £1,411 GBP per carat.

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

Caratlytics Diamond Price Index, August 2026: natural diamonds at 2,184 USD per carat and lab-grown at 464 USD per carat, a natural to lab ratio of 4.7 to 1. Marquise natural stones in the index: 2,114 USD per carat, -8.8% month on month. See the full index release

Figures come from live listings across more than 100 retailers and refresh daily. The index is a monthly release.

Last updated: September 2026

Available

1,069

Lowest Price

£570 GBP

Highest Price

£8,650 GBP

Average Price

£2,212 GBP

Market Intelligence

Retailers Selling

Price Spread

46.0%

Price Range

Price per carat distribution across retailers

$2,639/ct

10th Percentile

$1,609

Median

$2,639

90th Percentile

$4,010

Score Distribution

1.1K diamonds scored across 4 quality tiers

Excellent

118 (11.0%)

Very Good

319 (29.8%)

Good

356 (33.3%)

Average

276 (25.8%)

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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 20%

Lab-Grown I SI2Same specifications, lab-grown origin

Save 29%

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