How much does a 1.00 to 1.49ct I SI1 natural cushion diamond cost?

As of November 2026, 1.00 to 1.49ct I SI1 natural cushion diamonds typically cost HK$9,299 HKD to HK$29,966 HKD, with a median price of HK$17,312 HKD. There are currently 561 diamonds matching this specification available across retailers.

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

About 36% of these diamonds are available at multiple retailers, with an average price spread of 60%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.00 to 1.49ct I SI1 Natural Cushion

Quick answer

As of November 2026, there are 561 natural cushion diamonds with I colour and SI1 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run HK$9,299 HKD to HK$29,966 HKD, with a median of HK$17,312 HKD. At least 63 retailers stock this exact specification, and 36% of the stones appear at more than one of them, with an average price spread of 60%. Half of all listings fall between HK$12,736 HKD and HK$22,966 HKD per carat. The same specification in lab grown form lists at a median of about HK$4,398 HKD per carat. Over the last 30 days the median price moved -1.6% and the number of listings moved +8.8%.

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: November 2026

Available

561

Lowest Price

HK$6,473 HKD

Highest Price

HK$68,787 HKD

Average Price

HK$18,843 HKD

Market Intelligence

Retailers Selling

Cross Retailer %

35.6%

Price Spread

59.8%

30-Day Price Trend

-1.6%

30-Day Supply Change

+8.8%

Volatility (30d)

0.00

Price Range

Price per carat distribution across retailers

$2,180/ct

10th Percentile

$1,314

Median

$2,180

90th Percentile

$3,800

Score Distribution

1.2K diamonds scored across 4 quality tiers

Excellent

227 (18.7%)

Very Good

263 (21.7%)

Good

318 (26.2%)

Average

406 (33.4%)

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Consider Instead

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

J SI1J colour is visually identical to I to the naked eye

Save 24%

Lab-Grown I SI1Same specifications, lab-grown origin

Save 77%

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