Diamond sharpeners made in Marlborough, Massachusetts since 1976
✅ Made in USA
Where DMT sharpeners are made
Marlborough, Massachusetts
DMT’s plant at 85 Hayes Memorial Drive has been home to the company since 1983. Every sharpener in the line is made there.
Monocrystalline diamond
Micronized diamond is bonded to a precision-flat nickel substrate — the process DMT patented and still runs in-house.
Sold worldwide, built here
Product goes out to more than 50 countries, but production never left Massachusetts.
DMT states on its own site that it ‘continues to be an entirely Made in the USA company with all products manufactured in the company’s facility in Marlborough, Massachusetts.’ DMT has been part of Acme United Corporation, a U.S. publicly traded company, since 2016; manufacturing remained in Marlborough.
The story
DMT started in 1976 as a maker of industrial diamond grinding wheels. The sharpener business came out of a scrap problem: every grinding wheel left a round center punch-out, and someone at the company wondered whether that disc of diamond-bonded steel was useful on its own.
It was. A purchasing agent at L.L. Bean tested a sample, came back impressed, and worked with DMT’s engineers to turn the offcut into a finished product. L.L. Bean is still a DMT customer half a century later.
What DMT had stumbled into was a sharpening surface that solved several problems at once. It needed no oil, it cut faster than a stone, it never dished or grooved the way natural and ceramic stones do, and it would cut materials — tungsten carbide, ceramics, polycrystalline diamond inserts — that conventional abrasives simply could not touch.
The Diamond Whetstone, with its distinctive polka-dot interrupted surface, became the industry reference. Dia-Sharp, DuoSharp, Diafold, Aligner and the Dia-Flat lapping plate followed. The company now holds more than fifty patents and trademarks, and its products are widely copied.
Why they matter
Sharpening is a category where offshore production is the default. Walk any hardware aisle and the stones, steels and pull-through gadgets are almost all imported. DMT is the counterexample — a company that has kept an entire product line, not a token flagship item, on American soil for fifty years.
It matters more than it sounds. A diamond sharpener is a precision product: the plate has to be flat within thousandths of an inch and the diamond has to be evenly distributed and firmly bonded, or the tool cuts unevenly and sheds abrasive. That is process knowledge held by the people running the line, and it is exactly the kind of capability that disappears permanently when production is moved offshore to chase unit cost.
DMT also shows that American manufacturing survives on the strength of a real technical moat rather than sentiment. Woodworkers, chefs, machinists, ski technicians and knife makers buy DMT because it works, and it happens to be made here.
Featured products
Browse DMT diamond sharpeners available now in the Buy American store.
Frequently asked questions
Are DMT sharpeners made in the USA?
Yes. DMT states that all of its products are manufactured at its own facility in Marlborough, Massachusetts, and have been since the company moved there in 1983.
Who owns DMT?
DMT has been a brand of Acme United Corporation, a publicly traded American company headquartered in Shelton, Connecticut, since 2016. Manufacturing stayed in Marlborough.
What is the difference between a Diamond Whetstone and a Dia-Sharp?
The Diamond Whetstone uses DMT’s interrupted “polka dot” surface, which clears swarf and speeds up general sharpening. Dia-Sharp uses a continuous diamond surface, which is better for small or pointed tools that would catch on the gaps.
Do diamond sharpeners wear out?
They wear far more slowly than natural or ceramic stones and they never dish or groove, so the reference surface stays flat. Most users find a plate outlasts several conventional stones.
