How much does a 5.00ct+ I SI1 lab grown radiant diamond cost?

As of September 2026, 5.00ct+ I SI1 lab grown radiant diamonds typically cost $6,879 NZD to $151,048 NZD, with a median price of $19,423 NZD. There are currently 25 diamonds matching this specification available across retailers.

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

Compare prices across retailers on Carat Hunter to see all your options.

5.00ct+ I SI1 Lab Grown Radiant

Quick answer

As of September 2026, there are 25 lab grown radiant diamonds with I colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $6,879 NZD to $151,048 NZD, with a median of $19,423 NZD. At least 8 retailers stock this exact specification. Half of all listings fall between $314 NZD and $1,085 NZD per carat. The same specification in natural form lists at a median of about $26,796 NZD per carat.

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

Caratlytics Diamond Price Index, August 2026: natural diamonds at 2,184 USD per carat and lab-grown at 464 USD per carat, a natural to lab ratio of 4.7 to 1. Radiant lab grown stones in the index: 473 USD per carat, -12.5% month on month. See the full index release

Figures come from live listings across more than 100 retailers and refresh daily. The index is a monthly release.

Last updated: September 2026

Available

Lowest Price

$2,501 NZD

Highest Price

$352,908 NZD

Average Price

$52,243 NZD

Market Intelligence

Retailers Selling

Price Spread

200.3%

Price Range

Price per carat distribution across retailers

$224/ct

10th Percentile

$176

Median

$224

90th Percentile

$729

Score Distribution

25 diamonds scored across 4 quality tiers

Excellent

1 (4.0%)

Very Good

3 (12.0%)

Good

13 (52.0%)

Average

8 (32.0%)

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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