How much does a 1.00 to 1.49ct M SI1 natural round diamond cost?

As of November 6, 2026, 1.00 to 1.49ct M SI1 natural round diamonds typically cost £772 GBP to £1,969 GBP, with a median price of £1,144 GBP. There are currently 423 diamonds matching this specification available across retailers.

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

About 52% of these diamonds are available at multiple retailers, with an average price spread of 46%. A comparison tool like Carat Hunter lets you see all the prices side by side.

1.00 to 1.49ct M SI1 Natural Round

Quick answer

As of November 6, 2026, there are 423 natural round diamonds with M colour and SI1 clarity in the 1.00 to 1.49ct range available across retailers worldwide. Prices typically run £772 GBP to £1,969 GBP, with a median of £1,144 GBP. Half of all listings fall between £862 GBP and £1,331 GBP per carat. The same specification in lab grown form lists at a median of about £305 GBP per carat. Over the last 30 days the median price moved +1.1% and the number of listings moved +12.8%.

Three of the best scored stones at this specification right now:

Caratlytics Diamond Price Index, October 2026: natural diamonds at 2,202 USD per carat and lab-grown at 462 USD per carat, a natural to lab ratio of 4.8 to 1. Round natural stones in the index: 2,124 USD per carat, -6.9% month on month. See the full index release

Figures come from current listings across more than 125 retailers. The index is a monthly release.

Last updated: November 6, 2026

Available

423

Lowest Price

£506 GBP

Highest Price

£3,986 GBP

Average Price

£1,291 GBP

Market Intelligence

Cross Retailer %

51.5%

Price Spread

45.5%

30-Day Price Trend

+1.1%

30-Day Supply Change

+12.8%

Volatility (30d)

0.01

Price Range

Price per carat distribution across retailers

$1,388/ct

10th Percentile

$992

Median

$1,388

90th Percentile

$2,417

Score Distribution

423 diamonds scored across 4 quality tiers

Excellent

75 (17.7%)

Very Good

158 (37.4%)

Good

89 (21.0%)

Average

101 (23.9%)

Find Your Diamond

Search 423 M SI1 round diamonds and compare prices.

Search Diamonds

Related Specifications

D IF D VVS1 D VVS2 D VS1 D VS2 D SI1 E IF E VVS1 E VVS2 E VS1 E VS2 E SI1 F IF F VVS1 F VVS2 F VS1 F VS2 F SI1 G IF G VVS1 G VVS2 G VS1 G VS2 G SI1 H IF H VVS1 H VVS2 H VS1 H VS2 H SI1 I IF I VVS1 I VVS2 I VS1 I VS2 I SI1