How much does a 5.00ct+ I SI1 natural marquise diamond cost?

As of September 2026, 5.00ct+ I SI1 natural marquise diamonds typically cost $96,010 AUD to $187,296 AUD, with a median price of $146,366 AUD. There are currently 11 diamonds matching this specification available across retailers.

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

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

5.00ct+ I SI1 Natural Marquise

Quick answer

As of September 2026, there are 11 natural marquise diamonds with I colour and SI1 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $96,010 AUD to $187,296 AUD, with a median of $146,366 AUD. At least 10 retailers stock this exact specification. Half of all listings fall between $30,540 AUD and $37,342 AUD per carat. The same specification in lab grown form lists at a median of about $728 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. Marquise natural stones in the index: 2,114 USD per carat, -8.8% 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

Lowest Price

$84,112 AUD

Highest Price

$256,251 AUD

Average Price

$143,465 AUD