How much does a 3.00 to 4.99ct I SI2 natural round diamond cost?

As of October 2026, 3.00 to 4.99ct I SI2 natural round diamonds typically cost $24,769 AUD to $81,076 AUD, with a median price of $46,023 AUD. There are currently 465 diamonds matching this specification available across retailers.

Where can I find the best price on a I SI2 round diamond?

About 39% of these diamonds are available at multiple retailers, with an average price spread of 45%. A comparison tool like Carat Hunter lets you see all the prices side by side.

3.00 to 4.99ct I SI2 Natural Round

Quick answer

As of October 2026, there are 465 natural round diamonds with I colour and SI2 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run $24,769 AUD to $81,076 AUD, with a median of $46,023 AUD. At least 53 retailers stock this exact specification, and 39% of the stones appear at more than one of them, with an average price spread of 45%. Half of all listings fall between $10,114 AUD and $16,083 AUD per carat. The same specification in lab grown form lists at a median of about $733 AUD per carat. Over the last 30 days the median price moved -0.5% and the number of listings moved +2.2%.

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 natural stones in the index: 2,248 USD per carat, +7.6% 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

465

Lowest Price

$12,328 AUD

Highest Price

$163,467 AUD

Average Price

$50,448 AUD