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

As of October 2026, 1.50 to 1.99ct I SI1 natural round diamonds typically cost €3,609 EUR to €10,197 EUR, with a median price of €5,941 EUR. There are currently 1,362 diamonds matching this specification available across retailers.

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

About 40% of these diamonds are available at multiple retailers, with an average price spread of 47%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.50 to 1.99ct I SI1 Natural Round

Quick answer

As of October 2026, there are 1,362 natural round diamonds with I colour and SI1 clarity in the 1.50 to 1.99ct range available across retailers worldwide. Prices typically run €3,609 EUR to €10,197 EUR, with a median of €5,941 EUR. At least 68 retailers stock this exact specification, and 40% of the stones appear at more than one of them, with an average price spread of 47%. Half of all listings fall between €3,339 EUR and €5,313 EUR per carat. The same specification in lab grown form lists at a median of about €942 EUR per carat. Over the last 30 days the median price moved -1.5% and the number of listings moved +15.2%.

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. Round natural stones in the index: 2,248 USD per carat, +7.6% 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

1,362

Lowest Price

€1,973 EUR

Highest Price

€18,653 EUR

Average Price

€6,478 EUR