Sources and methods
CaratWatch uses only data published by government agencies and international bodies. Nothing is estimated, modeled or filled in; where an agency did not publish a number, the page says so.
Sources
| Agency | What we use | Updated |
|---|---|---|
| U.S. Census Bureau, International Trade API | U.S. imports and exports by 10-digit HTS code, country, port and state, monthly since 2013 | Monthly |
| India Ministry of Commerce, DGCI&S TRADESTAT | India's exports and imports by 8-digit code, value and carats, monthly since 2018 and by country each fiscal year | Monthly |
| General Administration of Customs of China | China's lab-grown diamond exports and imports by country, value and grams, monthly since 2022 | Quarterly |
| UN Comtrade | Every country's reported exports of lab-grown diamonds | Yearly |
| U.S. Bureau of Labor Statistics | Consumer prices for jewelry, import price indexes, jewelry retail margins | Monthly |
| U.S. Bureau of Economic Analysis | Personal spending on jewelry, monthly since 1959 | Monthly |
| Federal Reserve (FRED) | Exchange rates; jewelry store sales 1992-2021 | Daily / monthly |
| U.S. Census Bureau, ARTS, CBP, Nonemployer Statistics, ACS | Jewelry store sales and counts; marriages and income by state | Yearly |
| Kimberley Process | World production of natural rough diamonds | Yearly |
| U.S. International Trade Commission | Harmonized Tariff Schedule text and rates | As published |
| Electronic Code of Federal Regulations | FTC Guides for the Jewelry, Precious Metals, and Pewter Industries (16 CFR Part 23) | As amended |
Things to know before using the numbers
- U.S. Customs counts cut lab-grown diamonds by the stone, not by the carat. U.S. figures give a price per stone; per-carat prices come from India and China.
- Before 2022, lab-grown diamonds shared a customs code with other synthetic stones in the U.S. and most countries, so lab-grown series start in 2022 (India's from 2018 under its own code).
- India changed its codes in April 2022 and again in April 2023; series are joined across the changes, and April 2023 is unusually low.
- Before April 2022 India recorded rough lab-grown imports in kilograms, so no per-carat rough price exists for those months.
- Quarterly and yearly candles are built from monthly averages: open is the first month, close the last, high and low the highest and lowest months. They are not trading prices. Periods still in progress are drawn with a dashed outline.
- Two countries' records of the same trade rarely match (valuation, timing, transit). We show each country's own figures and do not merge them.
- Values marked 'not published' were withheld by the agency to protect confidentiality. They are not zero.
- China's code for polished lab-grown stones (71049190) includes some shipments declared at under $2 per carat. They are charted as reported, and the notes under the two China polished charts name the months and countries.
- Until mid-2024 China's exporters declared most rough lab-grown diamonds under code 7104.91.10 ('industrial, otherwise worked'), and after that under 7104.21 (rough). CaratWatch adds the two codes together for China's rough series and shows each code separately.
- China records imports by country of origin and exports by country of final destination, so China's and India's records of the same stones can differ, especially when the stones pass through Hong Kong.
- Average stone size divides India's record of carats shipped to the U.S. by the U.S. record of stones received from India; the two records do not always match, so treat it as an estimate.
- Freight and insurance is the difference between the CIF value and the customs value U.S. importers declare. It fell sharply in 2026; the records do not explain why.
- Public jewelers' figures come from their annual 10-K filings. Fiscal years end in different months (Signet: late January or early February; Brilliant Earth: December; Charles & Colvard: June since 2019).