How much does a 0.20 to 0.49ct I SI1 natural cushion diamond cost?

As of October 2026, 0.20 to 0.49ct I SI1 natural cushion diamonds typically cost £193 GBP to £432 GBP, with a median price of £269 GBP. There are currently 25 diamonds matching this specification available across retailers.

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

About 32% of these diamonds are available at multiple retailers, with an average price spread of 52%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.20 to 0.49ct I SI1 Natural Cushion

Quick answer

As of October 2026, there are 25 natural cushion diamonds with I colour and SI1 clarity in the 0.20 to 0.49ct range available across retailers worldwide. Prices typically run £193 GBP to £432 GBP, with a median of £269 GBP. At least 10 retailers stock this exact specification, and 32% of the stones appear at more than one of them, with an average price spread of 52%. Half of all listings fall between £713 GBP and £1,195 GBP per carat. Over the last 30 days the median price moved +2.1% and the number of listings moved +5.0%.

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. Cushion natural stones in the index: 2,948 USD per carat, +1.7% 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

£91 GBP

Highest Price

£780 GBP

Average Price

£294 GBP

Market Intelligence

Retailers Selling

Cross Retailer %

32.1%

Price Spread

52.4%

30-Day Price Trend

+2.1%

30-Day Supply Change

+5.0%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$1,232/ct

10th Percentile

$811

Median

$1,232

90th Percentile

$2,079

Score Distribution

63 diamonds scored across 4 quality tiers

Excellent

7 (11.1%)

Very Good

10 (15.9%)

Good

25 (39.7%)

Average

21 (33.3%)

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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