How much does a 3.00 to 4.99ct I SI1 natural round diamond cost?

As of September 2026, 3.00 to 4.99ct I SI1 natural round diamonds typically cost $31,093 AUD to $97,331 AUD, with a median price of $55,007 AUD. There are currently 1,305 diamonds matching this specification available across retailers.

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

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3.00 to 4.99ct I SI1 Natural Round

Quick answer

As of September 2026, there are 1,305 natural round diamonds with I colour and SI1 clarity in the 3.00 to 4.99ct range available across retailers worldwide. Prices typically run $31,093 AUD to $97,331 AUD, with a median of $55,007 AUD. At least 56 retailers stock this exact specification. Half of all listings fall between $15,489 AUD and $21,176 AUD per carat. The same specification in lab grown form lists at a median of about $2,647 AUD 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. Round natural stones in the index: 2,094 USD per carat, -3.8% 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

1,305

Lowest Price

$19,532 AUD

Highest Price

$195,030 AUD

Average Price

$61,236 AUD