How much does a 1.50 to 1.99ct I SI1 lab grown round diamond cost?

As of October 2026, 1.50 to 1.99ct I SI1 lab grown round diamonds typically cost $1,623 AUD to $4,725 AUD, with a median price of $2,021 AUD. There are currently 422 diamonds matching this specification available across retailers.

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

About 43% of these diamonds are available at multiple retailers, with an average price spread of 91%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI1 Lab Grown Round

Quick answer

As of October 2026, there are 422 lab grown round diamonds with I colour and SI1 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run $1,623 AUD to $4,725 AUD, with a median of $2,021 AUD. At least 35 retailers stock this exact specification, and 43% of the stones appear at more than one of them, with an average price spread of 91%. Half of all listings fall between $1,291 AUD and $2,650 AUD per carat. The same specification in natural form lists at a median of about $6,679 AUD per carat. Over the last 30 days the median price moved -8.1% and the number of listings moved +9.7%.

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. Round lab grown stones in the index: 414 USD per carat, -5.0% 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

422

Lowest Price

$270 AUD

Highest Price

$8,498 AUD

Average Price

$2,863 AUD

Market Intelligence

Retailers Selling

Cross Retailer %

43.0%

Price Spread

90.7%

30-Day Price Trend

-8.1%

30-Day Supply Change

+9.7%

Volatility (30d)

0.02

Price Range

Price per carat distribution across retailers

$1,053/ct

10th Percentile

$462

Median

$1,053

90th Percentile

$1,978

Score Distribution

737 diamonds scored across 4 quality tiers

Excellent

392 (53.2%)

Very Good

42 (5.7%)

Good

59 (8.0%)

Average

244 (33.1%)

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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