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

As of September 2026, 5.00ct+ G SI1 lab grown marquise diamonds typically cost £631 GBP to £5,169 GBP, with a median price of £1,133 GBP. There are currently 26 diamonds matching this specification available across retailers.

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

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5.00ct+ G SI1 Lab Grown Marquise

Quick answer

As of September 2026, there are 26 lab grown marquise diamonds with G colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £631 GBP to £5,169 GBP, with a median of £1,133 GBP. At least 25 retailers stock this exact specification. Half of all listings fall between £161 GBP and £559 GBP per carat. The same specification in natural form lists at a median of about £25,008 GBP per carat.

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

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

£368 GBP

Highest Price

£6,646 GBP

Average Price

£2,036 GBP

Market Intelligence

Retailers Selling

Price Spread

150.3%

Price Range

Price per carat distribution across retailers

$356/ct

10th Percentile

$194

Median

$356

90th Percentile

$1,159

Score Distribution

26 diamonds scored across 4 quality tiers

Excellent

4 (15.4%)

Very Good

9 (34.6%)

Good

4 (15.4%)

Average

9 (34.6%)

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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