How much does a 3.00 to 4.99ct I SI1 natural marquise diamond cost?

As of November 2026, 3.00 to 4.99ct I SI1 natural marquise diamonds typically cost $25,882 USD to $49,422 USD, with a median price of $37,590 USD. There are currently 25 diamonds matching this specification available across retailers.

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

About 40% of these diamonds are available at multiple retailers, with an average price spread of 38%. A comparison tool like Carat Hunter lets you see all the prices side by side.

3.00 to 4.99ct I SI1 Natural Marquise

Quick answer

As of November 2026, there are 25 natural marquise diamonds with I color and SI1 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run $25,882 USD to $49,422 USD, with a median of $37,590 USD. At least 52 retailers stock this exact specification, and 40% of the stones appear at more than one of them, with an average price spread of 38%. Half of all listings fall between $10,780 USD and $15,934 USD per carat. The same specification in lab grown form lists at a median of about $309 USD per carat. Over the last 30 days the median price moved -3.3% and the number of listings moved +31.2%.

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

Caratlytics Diamond Price Index, October 2026: natural diamonds at 2,202 USD per carat and lab-grown at 462 USD per carat, a natural to lab ratio of 4.8 to 1. Marquise natural stones in the index: 2,177 USD per carat, -4.2% 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

$20,052 USD

Highest Price

$79,522 USD

Average Price

$37,339 USD

Market Intelligence

Retailers Selling

Cross Retailer %

39.8%

Price Spread

37.7%

30-Day Price Trend

-3.3%

30-Day Supply Change

+31.2%

Volatility (30d)

0.02

Price Range

Price per carat distribution across retailers

$13,661/ct

10th Percentile

$9,183

Median

$13,661

90th Percentile

$17,900

Score Distribution

49 diamonds scored across 4 quality tiers

Excellent

9 (18.4%)

Very Good

17 (34.7%)

Good

13 (26.5%)

Average

10 (20.4%)

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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