How much does a 0.20 to 0.49ct I SI1 natural marquise diamond cost?

As of October 2026, 0.20 to 0.49ct I SI1 natural marquise diamonds typically cost $252 USD to $575 USD, with a median price of $368 USD. There are currently 212 diamonds matching this specification available across retailers.

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

About 44% of these diamonds are available at multiple retailers, with an average price spread of 30%. A comparison tool like Carat Hunter lets you see all the prices side by side.

0.20 to 0.49ct I SI1 Natural Marquise

Quick answer

As of October 2026, there are 212 natural marquise diamonds with I color and SI1 clarity in the 0.20 to 0.49ct range available across retailers worldwide. Prices typically run $252 USD to $575 USD, with a median of $368 USD. At least 14 retailers stock this exact specification, and 44% of the stones appear at more than one of them, with an average price spread of 30%. Half of all listings fall between $1,155 USD and $1,559 USD per carat. The same specification in lab grown form lists at a median of about $603 USD per carat. Over the last 30 days the median price moved -6.9% and the number of listings moved -2.4%.

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: October 2026

Available

212

Lowest Price

$154 USD

Highest Price

$1,259 USD

Average Price

$400 USD