Diamond Watcher

Diamond Price Index

Latest snapshot: September 2026

Diamond prices vary wildly between retailers for the exact same stone. Every month, we track real listings across major retailers for a fixed set of shapes and carats — so you can see who's actually cheaper, and exactly how much less lab-grown diamonds cost than natural ones.

In September 2026, lab-grown diamonds priced 87% below natural diamonds on average across Ritani, Blue Nile, Rare Carat, and Brilliance. The widest single gap was in 3ct Oval (natural), where Rare Carat ($43,285) undercut Blue Nile ($50,914) by $7,629.

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Lab-grown vs. natural

87% cheaper
On average, lab-grown diamonds price 87% below natural diamonds of the same shape, carat, color and clarity across Ritani, Blue Nile, Rare Carat, and Brilliance this month.
Shape
Carat
Type

Price grid — shape × carat

Median price, natural diamonds, color G / clarity VS1 — dashed cells are averaged from fewer than 4 retailers

Round$845$3,156$8,763$19,732$46,746Oval$769$3,662$9,948$21,300$46,5563/4 retailersCushion$756$1,9423/4 retailers$6,7593/4 retailers$15,0623/4 retailers$44,2003/4 retailers0.5ct1ct1.5ct2ct3ct

Retailer comparison

Round, 1ct, G / VS1, natural

RitaniBlue NileRare CaratBrilliance
Brilliance$2,196● cheapestRare Carat$2,870Ritani$3,461Blue Nile$4,099

Price trend over time

Round, 1ct, G / VS1, natural — median across retailers

AugSep

Natural vs. lab-grown premium

How much more natural costs than lab-grown, by shape (1ct, G / VS1)

Oval82% cheaper*Round71% cheaper*Cushion63% cheaper*

* averaged from fewer than 4 retailers on one or both sides

The 1-carat price cliff

Round, natural, G / VS1 — median price by displayed carat weight

Jumping from 1ct to 1.01ct costs $846 more (27%) — despite a barely noticeable size difference. Retailers price by displayed carat weight, not actual weight.

0.9ct1ct1.01ct1.05ct

Frequently Asked Questions

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Past reports

Median prices from Ritani, Blue Nile, Rare Carat, and Brilliance listings matching each spec. Updated monthly.