How much does a 3.00 to 4.99ct I SI1 natural cushion diamond cost?

As of November 6, 2026, 3.00 to 4.99ct I SI1 natural cushion diamonds typically cost $38,107 NZD to $125,802 NZD, with a median price of $68,593 NZD. There are currently 309 diamonds matching this specification available across retailers.

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

About 44% of these diamonds are available at multiple retailers, with an average price spread of 47%. A comparison tool like Carat Hunter lets you see all the prices side by side.

3.00 to 4.99ct I SI1 Natural Cushion

Quick answer

As of November 6, 2026, there are 309 natural cushion diamonds with I colour and SI1 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run $38,107 NZD to $125,802 NZD, with a median of $68,593 NZD. Half of all listings fall between $16,002 NZD and $25,626 NZD per carat. The same specification in lab grown form lists at a median of about $702 NZD per carat. Over the last 30 days the median price moved -0.7% and the number of listings moved +16.3%.

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

Caratlytics Diamond Price Index, October 2026: natural diamonds at 2,202 USD per carat and lab-grown at 462 USD per carat, a natural to lab ratio of 4.8 to 1. Cushion natural stones in the index: 2,881 USD per carat, -2.5% month on month. See the full index release

Figures come from current listings across more than 125 retailers. The index is a monthly release.

Last updated: November 6, 2026

Available

309

Lowest Price

$20,609 NZD

Highest Price

$222,627 NZD

Average Price

$76,869 NZD

Market Intelligence

Cross Retailer %

43.7%

Price Spread

46.9%

30-Day Price Trend

-0.7%

30-Day Supply Change

+16.3%

Volatility (30d)

0.00

Price Range

Price per carat distribution across retailers

$11,369/ct

10th Percentile

$6,982

Median

$11,369

90th Percentile

$16,818

Score Distribution

309 diamonds scored across 4 quality tiers

Excellent

65 (21.0%)

Very Good

87 (28.2%)

Good

65 (21.0%)

Average

92 (29.8%)

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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