Product classification
HS code for Diamond millstones: 6804.21
Millstones, grindstones, grinding wheels and the like, of agglomerated synthetic or natural diamond.
Classification of diamond millstones under HS 6804.21
Diamond millstones and grinding wheels are classified under HS code 6804.21. This heading covers millstones, grindstones, grinding wheels, and similar articles without frameworks, specifically those made of agglomerated synthetic or natural diamond. The classification is determined by the abrasive material that performs the work on the surface of the tool. In this case, the presence of diamond as the abrasive agent dictates the use of 6804.21. These articles are typically manufactured by bonding diamond grit with various agents such as resin, metal, or vitrified bonds. They are essential in industries requiring high-precision cutting, grinding, and polishing of extremely hard materials like stone, glass, ceramics, and certain alloys. It is important to note that this heading excludes tools that have a permanent framework or handle, as those are generally classified in Chapter 82 as tools or parts of tools.
- Covers
- Diamond grinding wheels for glass edging and beveling
- Diamond cutting discs for granite, marble, and concrete
- Diamond honing stones for engine cylinder finishing
- Diamond-impregnated millstones for industrial grinding
- Diamond polishing wheels for semiconductor wafer fabrication
- Also under 6804.21
- Norton Abrasives diamond wheels
- Tyrolit diamond cutting discs
- 3M Cubitron diamond abrasives
- Bosch diamond saw blades
Codes often confused with 6804.21
Common mistake. Diamond millstones are frequently misclassified under 8207 (Interchangeable tools for hand tools or machine tools) or 6804.22 (Millstones of other agglomerated abrasives). 8207 is often used incorrectly for diamond wheels that are part of a tool set, but 6804 is the specific heading for the grinding wheels themselves. 6804.22 is reserved for wheels made of materials like silicon carbide or aluminum oxide, not diamond.
Top exporters and importers of HS 680421 (the code used for diamond millstones), 2025
In 2025, the largest exporter of HS 680421 (the code used for diamond millstones) in UN Comtrade data was China, with 14% of world exports; the largest importer in UN Comtrade data was China, with 16% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Figures cover everything classified under HS 680421, not only diamond millstones.
Top exporters 2025 · share of world exports
- 1 China $253M 14% of world exports
- 2 South Korea $236M 13% of world exports
- 3 Italy $227M 12% of world exports
World total: $1.8B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $353M 16% of world imports
- 2 United States $230M 11% of world imports
- 3 Germany $191M 8.7% of world imports
World total: $2.2B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Brazil NCM codes for diamond millstones
Brazil splits HS 6804.21 into 3 NCM codes. Pick the one that matches your product:
- 6804.21.11Resin-bonded diamond wheels, under 53.34 cm
- 6804.21.19Other diamond wheels under 53.34 cm diameter
- 6804.21.90Diamond grinding wheels, 53.34 cm or more
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
Questions about diamond millstones
What is the HS code for Diamond millstones?
The HS code for Diamond millstones is 680421 (Millstones, grindstones, grinding wheels and the like; of agglomerated synthetic or natural diamond). The correct HS code for millstones and grinding wheels made of agglomerated diamond is 6804.21.
How do I classify Diamond millstones for customs?
Diamond millstones is classified under HS code 680421 — Millstones, grindstones, grinding wheels and the like; of agglomerated synthetic or natural diamond. This is a 6-digit subheading level code.
Does this code include diamond-tipped drill bits?
No, diamond-tipped drill bits are classified under 8207.50 as interchangeable tools for drilling, as they are considered tools rather than millstones or grinding wheels.
Which countries are the top exporters of diamond millstones (HS 680421)?
In 2025, the top exporters of HS 680421 (the code used for diamond millstones) in UN Comtrade data were China ($253M, 14% of world exports), South Korea ($236M) and Italy ($227M). World exports came to about $1.8B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of diamond millstones (HS 680421)?
In 2025, the top importers of HS 680421 (the code used for diamond millstones) in UN Comtrade data were China ($353M, 16% of world imports), the United States ($230M) and Germany ($191M). World imports came to about $2.2B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Is the HS code for Diamond millstones the same in all countries?
The base HS code 680421 for Diamond millstones is internationally standardized for the first 6 digits across 200+ countries. Individual countries may add additional digits for national tariff lines and specific classifications.
What is the NCM code for diamond millstones in Brazil?
Brazil splits HS 680421 into 3 NCM codes, so the right one for diamond millstones depends on the product's details: 6804.21.11 (Resin-bonded diamond wheels, under 53.34 cm), 6804.21.19 (Other diamond wheels under 53.34 cm diameter), 6804.21.90 (Diamond grinding wheels, 53.34 cm or more).