How much does a 0.20 to 0.49ct D SI1 natural marquise diamond cost?

As of October 2026, 0.20 to 0.49ct D SI1 natural marquise diamonds typically cost £233 GBP to £528 GBP, with a median price of £359 GBP. There are currently 1,435 diamonds matching this specification available across retailers.

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

About 42% of these diamonds are available at multiple retailers, with an average price spread of 39%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.20 to 0.49ct D SI1 Natural Marquise

Quick answer

As of October 2026, there are 1,435 natural marquise diamonds with D colour and SI1 clarity in the 0.20 to 0.49ct range available across retailers worldwide. Prices typically run £233 GBP to £528 GBP, with a median of £359 GBP. At least 27 retailers stock this exact specification, and 42% of the stones appear at more than one of them, with an average price spread of 39%. Half of all listings fall between £1,034 GBP and £1,491 GBP per carat. The same specification in lab grown form lists at a median of about £666 GBP per carat. Over the last 30 days the median price moved -6.3% and the number of listings moved -4.9%.

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

1,435

Lowest Price

£139 GBP

Highest Price

£1,118 GBP

Average Price

£379 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

41.9%

Price Spread

38.7%

30-Day Price Trend

-6.3%

30-Day Supply Change

-4.9%

Volatility (30d)

0.02

Price Range

Price per carat distribution across retailers

$1,582/ct

10th Percentile

$1,064

Median

$1,582

90th Percentile

$2,531

Score Distribution

2.6K diamonds scored across 4 quality tiers

Excellent

217 (8.4%)

Very Good

578 (22.4%)

Good

870 (33.6%)

Average

921 (35.6%)

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Consider Instead

Save money without compromising on what matters. These alternatives are visually similar but cost less.

Lab-Grown D SI1Same specifications, lab-grown origin

Save 29%

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