How much does a 5.00ct+ I SI2 natural marquise diamond cost?

As of September 2026, 5.00ct+ I SI2 natural marquise diamonds typically cost $43,679 USD to $168,312 USD, with a median price of $88,258 USD. There are currently 25 diamonds matching this specification available across retailers.

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

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5.00ct+ I SI2 Natural Marquise

Quick answer

As of September 2026, there are 25 natural marquise diamonds with I color and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $43,679 USD to $168,312 USD, with a median of $88,258 USD. At least 8 retailers stock this exact specification. Half of all listings fall between $15,809 USD and $19,249 USD 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

Lowest Price

$36,670 USD

Highest Price

$992,086 USD

Average Price

$130,739 USD

Market Intelligence

Retailers Selling

Price Spread

20.6%

Price Range

Price per carat distribution across retailers

$16,669/ct

10th Percentile

$12,525

Median

$16,669

90th Percentile

$20,174

Score Distribution

25 diamonds scored across 4 quality tiers

Excellent

2 (8.0%)

Very Good

10 (40.0%)

Good

5 (20.0%)

Average

8 (32.0%)

Find Your Diamond

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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

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I I1I1 inclusions are not visible without magnification

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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