How much does a 1.50 to 1.99ct I SI1 natural marquise diamond cost?

As of October 2026, 1.50 to 1.99ct I SI1 natural marquise diamonds typically cost $9,890 NZD to $31,703 NZD, with a median price of $15,464 NZD. There are currently 88 diamonds matching this specification available across retailers.

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

About 34% of these diamonds are available at multiple retailers, with an average price spread of 39%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI1 Natural Marquise

Quick answer

As of October 2026, there are 88 natural marquise diamonds with I colour and SI1 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run $9,890 NZD to $31,703 NZD, with a median of $15,464 NZD. At least 59 retailers stock this exact specification, and 34% of the stones appear at more than one of them, with an average price spread of 39%. Half of all listings fall between $9,479 NZD and $13,979 NZD per carat. The same specification in lab grown form lists at a median of about $1,771 NZD per carat. Over the last 30 days the median price moved -4.8% and the number of listings moved +21.7%.

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. Marquise natural stones in the index: 2,268 USD per carat, +10.8% 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

Lowest Price

$6,462 NZD

Highest Price

$50,217 NZD

Average Price

$18,551 NZD