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

As of November 2026, 5.00ct+ I SI1 lab grown marquise diamonds typically cost $4,516 AUD to $4,516 AUD, with a median price of $4,516 AUD. There are currently 1 diamonds matching this specification available across retailers.

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

About 25% of these diamonds are available at multiple retailers, with an average price spread of 64%. A comparison tool like Carat Hunter lets you see all the prices side by side.

5.00ct+ I SI1 Lab Grown Marquise

Quick answer

As of November 2026, there are 1 lab grown marquise diamonds with I colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $4,516 AUD to $4,516 AUD, with a median of $4,516 AUD. At least 12 retailers stock this exact specification, and 25% of the stones appear at more than one of them, with an average price spread of 64%. Half of all listings fall between $345 AUD and $774 AUD per carat. The same specification in natural form lists at a median of about $35,461 AUD per carat.

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

8.18ct Marquise I SI1, IGI, grade B, from $4,516 AUD

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 lab grown stones in the index: 485 USD per carat, -3.2% 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

$4,516 AUD

Highest Price

$4,516 AUD

Average Price

$4,516 AUD

Market Intelligence

Retailers Selling

Cross Retailer %

25.0%

Price Spread

64.3%

Price Range

Price per carat distribution across retailers

$469/ct

10th Percentile

$133

Median

$469

90th Percentile

$808

Score Distribution

1 diamonds scored across 1 quality tiers

Good

1 (100.0%)

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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