# U.S. Patent 3,159,876 — Hall, "High Pressure Press" (cubic press)

**Type:** source
**Status:** Useful
**Confidence:** High
**Source Type:** patent
**Publisher:** U.S. Patent and Trademark Office
**Retrieved:** 2026-08-12
**URL:** https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/3159876
**Updated:** 2026-08-11

## Summary

The patent covering H. Tracy Hall's six-anvil press — the cubic press, the design that became the workhorse of industrial synthetic-diamond production. Like the tetrahedral press patent before it, it is filed from Provo, and it explicitly builds on that earlier application.

## Useful Claims

- Patent number 3,159,876, titled "High Pressure Press". Application serial no. 199,558, filed May 23, 1962 as a continuation of serial no. 851,855 of November 9, 1959; granted December 8, 1964.
- The face of the patent reads "Howard T. Hall, Provo, Utah, assignor to Research Corporation, New York, N.Y." — the same Provo inventor and the same assignee as the tetrahedral press.
- The specification names the lineage directly: "In my co-pending application, Serial No. 731,543, filed April 28, 1958, issued as Patent No. 2,918,699, December 29, 1959, there is disclosed a tetrahedral anvil type press." The cubic press is documented as a successor to the tetrahedral design in Hall's own words, on the record.
- The six-anvil embodiment is claimed and described: "the anvil devices … are six in number and when in the closed position, the six faces thereof define a regular four-sided prism", with one opposed pair on a common axis and the other four converging in a plane normal to it.
- On materials, the specification distinguishes duty by pressure: hardened steels such as AISI 4140 or 4340 for presses operating at not substantially more than 35,000 atmospheres, and cemented tungsten carbide where "substantially higher pressures are to be developed".

## Reliability Notes

Primary tier. A granted U.S. patent is a dated public instrument the USPTO must preserve, retrievable by number indefinitely; no archive snapshot is owed. The URL is the issuing body's own PDF of the grant.

Scope. This settles the cubic-press design, its dates, its assignee, and its documented descent from the tetrahedral press. It says nothing about the commercial history the fact page describes — the transfer of cubic-press technology abroad around 1960, the share of the world's diamond powder now made on presses of this family, or the founding of MegaDiamond and Novatek. Those remain sourced to secondary accounts.

## Related Pages

- [H. Tracy Hall's Diamond Presses](h-tracy-hall-diamond-presses.md)
- [U.S. Patent 2,918,699 — Hall, "High Pressure Press" (tetrahedral press)](hall-tetrahedral-press-patent-us2918699.md)