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.
Latest release: July 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 | 1,625,153 | 70.4% | 60% | $4.14B |
| Lab-grown | 2,683,502 | 117.8% | 90.5% | $3.15B |
Summed across 4,308,655 certified stones listed by two or more retailers, the total active cross-retailer spread is about $7.29B.
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: Caratlytics Diamond Price Index, release July 2026, caratlytics.com. Data is licensed CC BY 4.0; attribution to 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.