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

As of October 2026, 5.00ct+ H SI1 lab grown marquise diamonds typically cost £673 GBP to £3,090 GBP, with a median price of £1,758 GBP. There are currently 3 diamonds matching this specification available across retailers.

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

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5.00ct+ H SI1 Lab Grown Marquise

Quick answer

As of October 2026, there are 3 lab grown marquise diamonds with H colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run £673 GBP to £3,090 GBP, with a median of £1,758 GBP.

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 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: October 2026

Available

Lowest Price

£433 GBP

Highest Price

£6,777 GBP

Average Price

£1,967 GBP

Score Distribution

7 diamonds scored across 4 quality tiers

Excellent

1 (14.3%)

Very Good

1 (14.3%)

Good

3 (42.9%)

Average

2 (28.6%)

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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