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

As of November 2026, 1.50 to 1.99ct I SI1 natural marquise diamonds typically cost $5,579 USD to $17,790 USD, with a median price of $8,812 USD. There are currently 77 diamonds matching this specification available across retailers.

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

About 32% 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 November 2026, there are 77 natural marquise diamonds with I color and SI1 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run $5,579 USD to $17,790 USD, with a median of $8,812 USD. At least 58 retailers stock this exact specification, and 32% of the stones appear at more than one of them, with an average price spread of 39%. Half of all listings fall between $5,316 USD and $7,878 USD per carat. The same specification in lab grown form lists at a median of about $967 USD per carat. Over the last 30 days the median price moved -4.4% and the number of listings moved +18.4%.

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: November 2026

Available

Lowest Price

$3,606 USD

Highest Price

$28,188 USD

Average Price

$10,416 USD