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

As of October 2026, 5.00ct+ I SI2 natural marquise diamonds typically cost $55,659 CAD to $165,606 CAD, with a median price of $100,555 CAD. There are currently 12 diamonds matching this specification available across retailers.

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

About 39% of these diamonds are available at multiple retailers, with an average price spread of 36%. A comparison tool like Carat Hunter lets you see all the prices side by side.

5.00ct+ I SI2 Natural Marquise

Quick answer

As of October 2026, there are 12 natural marquise diamonds with I color and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $55,659 CAD to $165,606 CAD, with a median of $100,555 CAD. At least 21 retailers stock this exact specification, and 39% of the stones appear at more than one of them, with an average price spread of 36%. Half of all listings fall between $18,048 CAD and $25,804 CAD per carat. Over the last 30 days the median price moved -1.9% and the number of listings moved +29.1%.

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

Lowest Price

$49,646 CAD

Highest Price

$355,865 CAD

Average Price

$115,459 CAD

Market Intelligence

Retailers Selling

Cross Retailer %

39.4%

Price Spread

36.0%

30-Day Price Trend

-1.9%

30-Day Supply Change

+29.1%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$15,440/ct

10th Percentile

$11,255

Median

$15,440

90th Percentile

$19,950

Score Distribution

22 diamonds scored across 4 quality tiers

Excellent

5 (22.7%)

Very Good

6 (27.3%)

Good

8 (36.4%)

Average

3 (13.6%)

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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