Diamond Foundry Says It Has Grown a Diamond Crystal as Wide as a Chip Wafer
Diamond Foundry announced on Nov. 5, 2026, that it has grown a single crystal of diamond 200 millimeters in diameter, in one continuous piece. The company calls it "the first-ever D200mm single-crystal diamond." No independent measurement of the crystal, or of that priority claim, has been published.
Diamond Foundry says it is working to turn single-crystal diamond from a scarce material measured in gemstones into a semiconductor substrate it can make at scale. Diamond carries heat away better than any other bulk material, and the company says crystal size, rather than anything about the material itself, has been the limit on putting it under chips instead of into jewelry. Silicon chip factories handle wafers at a few standard diameters, and the one the company says it has matched is among them.
What Diamond Foundry has shown is a single crystal, photographed as grown and unpolished outside its South San Francisco headquarters, and not a finished wafer. The company's announcement gives no figures for the crystal's thickness, its flaws, how often a growth run succeeds, or what it costs, and does not say when the crystal was grown. Chief executive Martin Roscheisen presented it at the Carbon Semi 2026 conference.
Roscheisen said in the announcement, "This is one of those milestones that once seemed almost impossible." He said of the two scientists whose work the company credits, "They kept going when the prevailing view was that single-crystal diamond simply could not be made at this scale," and said the result "makes D300mm predictable as well," the company's expectation of a crystal 300 millimeters across that it has not shown.
That work predates the company. Diamond Foundry says Stefan Gsell and Martin Fischer have pursued scalable single-crystal diamond growth for 25 years, and that the two joined it in 2022 when it acquired Augsburg Diamond Technology, known as Audiatec. The company says reaching this diameter took advances in plasma physics, reactor engineering and process control.
