How much does a 5.00ct+ I SI1 natural cushion diamond cost?

As of October 2026, 5.00ct+ I SI1 natural cushion diamonds typically cost $71,065 SGD to $231,727 SGD, with a median price of $108,826 SGD. There are currently 19 diamonds matching this specification available across retailers.

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

About 26% of these diamonds are available at multiple retailers, with an average price spread of 40%. A comparison tool like Carat Hunter lets you see all the prices side by side.

5.00ct+ I SI1 Natural Cushion

Quick answer

As of October 2026, there are 19 natural cushion diamonds with I colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $71,065 SGD to $231,727 SGD, with a median of $108,826 SGD. At least 45 retailers stock this exact specification, and 26% of the stones appear at more than one of them, with an average price spread of 40%. Half of all listings fall between $17,163 SGD and $25,880 SGD per carat. The same specification in lab grown form lists at a median of about $4,094 SGD per carat. Over the last 30 days the median price moved -1.8% and the number of listings moved -3.5%.

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

$53,527 SGD

Highest Price

$468,118 SGD

Average Price

$133,817 SGD

Market Intelligence

Retailers Selling

Cross Retailer %

26.2%

Price Spread

40.4%

30-Day Price Trend

-1.8%

30-Day Supply Change

-3.5%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$16,900/ct

10th Percentile

$11,194

Median

$16,900

90th Percentile

$22,434

Score Distribution

42 diamonds scored across 4 quality tiers

Excellent

6 (14.3%)

Very Good

6 (14.3%)

Good

11 (26.2%)

Average

19 (45.2%)

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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