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

As of September 2026, 3.00 to 4.99ct I SI1 lab grown marquise diamonds typically cost $8,191 AUD to $12,449 AUD, with a median price of $10,512 AUD. There are currently 53 diamonds matching this specification available across retailers.

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

Compare prices across retailers on Carat Hunter to see all your options.

3.00 to 4.99ct I SI1 Lab Grown Marquise

Quick answer

As of September 2026, there are 53 lab grown marquise diamonds with I colour and SI1 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run $8,191 AUD to $12,449 AUD, with a median of $10,512 AUD. At least 8 retailers stock this exact specification. Half of all listings fall between $2,604 AUD and $2,884 AUD per carat. The same specification in natural form lists at a median of about $25,051 AUD per carat.

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

3.70ct Marquise I SI1, IGI, score 76 of 100, from $1,677 AUD

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 lab grown stones in the index: 500 USD per carat, -14.7% 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

$1,677 AUD

Highest Price

$83,548 AUD

Average Price

$12,599 AUD

Market Intelligence

Retailers Selling

Price Spread

10.3%

Price Range

Price per carat distribution across retailers

$1,759/ct

10th Percentile

$395

Median

$1,759

90th Percentile

$1,880

Score Distribution

53 diamonds scored across 3 quality tiers

Very Good

1 (1.9%)

Good

50 (94.3%)

Average

2 (3.8%)

Find Your Diamond

Search 53 I SI1 marquise diamonds and compare prices.

Search Diamonds

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