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Diamond Watcher
Diamond Price Index
Report for 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 89% 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.
Lab-grown vs. natural
89% cheaper
On average, lab-grown diamonds price 89% 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
Retailer comparison
Round, 1ct, G / VS1, natural
RitaniBlue NileRare CaratBrilliance
Natural vs. lab-grown premium
How much more natural costs than lab-grown, by shape (1ct, G / VS1)
* 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.
Frequently Asked Questions
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