How much does a 5.00ct+ I SI1 natural marquise diamond cost?

As of November 2026, 5.00ct+ I SI1 natural marquise diamonds typically cost €61,621 EUR to €78,975 EUR, with a median price of €67,224 EUR. There are currently 2 diamonds matching this specification available across retailers.

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

About 33% of these diamonds are available at multiple retailers, with an average price spread of 48%. A comparison tool like Carat Hunter lets you see all the prices side by side.

5.00ct+ I SI1 Natural Marquise

Quick answer

As of November 2026, there are 2 natural marquise diamonds with I color and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run €61,621 EUR to €78,975 EUR, with a median of €67,224 EUR. At least 30 retailers stock this exact specification, and 33% of the stones appear at more than one of them, with an average price spread of 48%. Half of all listings fall between €15,297 EUR and €26,021 EUR per carat. The same specification in lab grown form lists at a median of about €420 EUR per carat. Over the last 30 days the median price moved -2.6% and the number of listings moved +27.5%.

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: November 2026

Available

Lowest Price

€60,634 EUR

Highest Price

€125,527 EUR

Average Price

€69,273 EUR

Market Intelligence

Retailers Selling

Cross Retailer %

33.3%

Price Spread

48.1%

30-Day Price Trend

-2.6%

30-Day Supply Change

+27.5%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$24,910/ct

10th Percentile

$14,765

Median

$24,910

90th Percentile

$31,195

Score Distribution

6 diamonds scored across 4 quality tiers

Excellent

1 (16.7%)

Very Good

1 (16.7%)

Good

3 (50.0%)

Average

1 (16.7%)

Find Your Diamond

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Consider Instead

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

I SI2SI2 inclusions are not visible without magnification

Save 39%

Lab-Grown I SI1Same specifications, lab-grown origin

Save 98%

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