Caratlytics Diamond Price Index
A monthly index of retail diamond prices. Each release reports the median USD per carat for natural and lab-grown diamonds, computed from a systematic sample of live listings across more than one hundred retailers, with the full series downloadable as CSV and JSON under CC BY 4.0.
In September 2026, the median natural diamond listed at 2,335 USD per carat, up 7.5 percent on August 2026, across 1,270,622 observed listings. Lab-grown diamonds listed at a median of 443 USD per carat, down 4.8 percent, across 2,183,916 observed listings. Natural stones cost 5.3 times as much per carat as lab-grown, a premium of 427 percent. By shape, the largest natural moves on the month were pear (up 13.7 percent) and Asscher (down 3.3 percent). 2,930,286 certified stones were listed by two or more retailers; the same stone was priced 76 percent apart at the median for natural and 219 percent for lab-grown. Since the first release in December 2025, the natural median has moved up 10.2 percent and the lab-grown median down 43.3 percent. The figures come from a systematic 1 in 10 sample of live listings across 140+ retailers, in pinned-rate USD, and are licensed CC BY 4.0.
Latest release: September 2026
Chart values are medians. Shaded band shows the interquartile range for the overall market.
Cross-retailer price spread
When the same certificate is listed by two or more retailers, the spread between the cheapest and the most expensive listing measures market dispersion. Lab-grown dispersion runs far higher than natural.
| Diamonds matched at 2+ retailers | Average spread | Median spread | Total spread | |
|---|---|---|---|---|
| Natural | 1,507,445 | 90.1% | 75.6% | $3.76B |
| Lab-grown | 1,422,841 | 207.2% | 218.9% | $2.28B |
Summed across 2,930,286 certified stones listed by two or more retailers, the total active cross-retailer spread is about $6.04B.
Index methodology
- Sample: a systematic 1 in 10 sample of listings (by listing identifier), each contributing its most recent observed price in the calendar month. Monthly observation volumes run in the millions.
- Unit: USD per carat under the platform's pinned conversion rates, which act as a fixed unit of account. The series moves when retailers reprice, never on currency fluctuations.
- Filters: carat 0.25 to 10, price 100 to 100,000 USD per carat, positive prices only. The series begins December 2025, the first month of full collection coverage.
- Segments: natural and lab-grown, classified from the stone's certified origin, plus the overall market. Quartiles are published alongside medians.
- Revisions: releases are immutable once published. A correction is published as a new release with a changelog entry, never as a silent edit.
Cite as: Carat Hunter, Caratlytics Diamond Price Index, release September 2026, caratlytics.com. Data is licensed CC BY 4.0; attribution to Carat Hunter and Caratlytics is required.
By segment
Deeper cuts of the same open dataset, each downloadable.
Lab-grown vs natural over time
How the median price per carat of natural and lab-grown diamonds has moved month by month, and the premium natural still commands. Open data, updated monthly.
Median price by shape
Median USD per carat by diamond shape, natural and lab-grown, tracked monthly. Lines show natural medians; the full natural and lab series for every shape are in the download.
Price by grading laboratory
Median USD per carat by grading laboratory, tracked monthly. Differences reflect both the stones each lab tends to grade and how the market prices each report.
Explore the live data on Carat Hunter
The index is computed from the same listings Carat Hunter searches every day. These pages show the current market behind the monthly figures.