What Tomei Diamond does

Tomei Diamond Co., Ltd. is a privately held Japanese industrial materials manufacturer headquartered in Oyama, Tochigi Prefecture, with approximately 120 employees and a founding history dating to 1953 (as Ishizuka Research Institute). The company designs, manufactures, and sells synthetic industrial diamond and cubic boron nitride (cBN) materials, including micron-, nano-, and mesh-size diamond and cBN powders; polycrystalline diamond (PCD) and polycrystalline cBN (PcBN) sintered bodies; specialty large-format sinters; CVD polycrystalline diamond substrates; and boron-doped diamond electrodes. Core production is enabled by self-developed 20,000-ton high-temperature high-pressure synthesis equipment and proprietary CVD diamond synthesis reactors, with the company credited with Japan's first successful diamond synthesis (1961) and first mass production of synthetic diamond powder (1962).

The business sells primarily B2B to industrial customers across three verticals: semiconductor and electronic components (dicing, back grinding, polishing, wire saws, heat sinks); automotive and machinery (cutting and grinding tools for non-ferrous and ferrous metals, cemented carbide processing, wear-resistant parts); and stone/civil engineering (concrete and stone cutting, core drilling, polishing). Distribution in Japan is direct (Tokyo and Osaka sales offices), supplemented by trading-company intermediation on customer request; overseas markets are served via country-specific agents and a wholly-owned U.S. subsidiary (TOMEI DIAMOND USA Inc., Georgetown, Kentucky). Newer product lines extend the portfolio into boron-doped diamond electrodes for ozone water generation and CO2 conversion, and into lab-grown consumer jewelry under the Tsumugi Diamond and QR Diamond brands. Pricing is quote-based and not publicly disclosed; minimum order quantity for powder products is 100ct (20g), and standard in-stock items ship within 1-2 days.

Revenue model is one-time product sales across the full materials portfolio, with no disclosed subscription, licensing, or recurring revenue streams. Customer relationships are anchored by custom-order capability (grain size, shape, coating treatments, layer thickness tuning) and by co-development partnerships with university research laboratories. The company is closely held, family-led (Representative Director Hiromi Ishizuka), and has no disclosed parent company, external investors, or funding rounds.

Name

Tomei Diamond

Legal name

トーメイダイヤ株式会社

Website

https://tomeidiamond.co.jp

Company type

Private

Founded year

1954

Operating status

Operating

Headcount range

101–250 employees

Short description

Tomei Diamond is a Japanese industrial materials manufacturer that designs, produces, and sells synthetic diamond and cBN powders, sintered bodies, CVD substrates, and diamond electrodes to semiconductor, automotive, machinery, and construction customers.

Ownership category

akta.pro rank

Product category

Industrial Superhard Abrasives Manufacturing

NAICS

Nonmetallic Mineral Product Manufacturing (327)

SIC

Jewelry, Precious Metal (3911)

akta.pro primary industry

Synthetic/Lab-Grown Diamonds & Gemstones (Manufacturing & Trading) (CRAKAJAM)

akta.pro secondary industry

Lab-Grown Diamond Bridal Jewelry (CRAKACAF)

Keywords

• Industrial diamond materials
• Cubic boron nitride abrasives
• Sintered diamond tools
• Diamond electrode manufacturing
• Lab-grown diamond production

Headquarters

HQ city

Tochigi

HQ country

Japan

HQ region

Asia

Offices4 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Supply Chain, Operations, Personnel, Technology or R&D, Infrastructure, Marketing or Sales

Revenue model

1. Diamond and cBN powder manufacturing and sales: Manufactures and sells over 100 varieties of synthetic diamond powder and cBN powder across micron, nano, and mesh sizes for industrial applications such as cutting, grinding, and polishing tools. Revenue is generated through direct product sales with minimum order quantities of 100ct (20g).
2. Diamond and cBN sintered body (PCD/PcBN) manufacturing and sales: Produces sintered diamond and cBN compact products using high-temperature high-pressure methods, including standard and custom shapes for cutting, grinding, and wear-resistant applications in automotive and machinery sectors.
3. CVD diamond electrode manufacturing and sales: Manufactures boron-doped CVD diamond electrodes for ozone water generation, electrochemical sensors, CO2 conversion, and new material synthesis applications. Provided as cells/modules with material field support.
4. Lab-grown diamond (jewelry applications): Sells lab-grown diamonds for jewelry purposes, including branded products such as Tsumugi Diamond (memorial diamonds with biological material) and QR Diamond (QR-coded diamonds). Also supplies uniquely shaped lab-grown diamonds beyond standard rounds.

Pricing tiers

Go-to-market motion1 record

Distribution channels2 records

Marketing channels2 records

Core offering

Tomei Diamond designs, manufactures, and sells synthetic industrial diamond and cubic boron nitride (cBN) materials, including powders, sintered bodies (PCD/PcBN), CVD diamond substrates, and boron-doped diamond electrodes, for use in cutting, grinding, polishing, and water-treatment applications. It also produces gem-quality lab-grown diamonds for jewelry and memorial applications. Sales are conducted direct, through a U.S. subsidiary, and via trading-company intermediation.

Product overview

Tomei Diamond is a Japanese industrial diamond materials pioneer offering a comprehensive portfolio of synthetic diamond and cBN (cubic boron nitride) products. The core product line includes diamond powder (available in nano, micron, and mesh sizes), cBN powder, diamond sintered bodies (PCD), cBN sintered bodies (PcBN), special sintered bodies, CVD diamond substrates/plates, and diamond electrodes. Beyond industrial applications, the company has expanded into lab-grown diamonds for jewelry, including unique offerings like Tsubu Diamond (memorial diamonds) and QR Diamond (QR-encoded diamonds). Products serve three main application areas: semiconductors and electronic components, automobiles and machinery, and stone/civil engineering. The company operates from Oyama Plant in Tochigi Prefecture with sales offices in Tokyo and Osaka, plus a U.S. subsidiary.

Differentiator

Problem solved

Functional benefit

Brands

• 紡ぐダイヤ (Tsubugu Diamond): A synthetic diamond embedded with keepsakes such as umbilical cord or baby teeth, creating a unique memorial diamond.
• QRダイヤ (QR Diamond)
• Miracle Diamond (MD)

Products and services

• Diamond Powder HPHT-synthetic industrial diamond abrasive powder supplied in multiple grades and grain sizes for cutting, grinding, and polishing tool manufacturers; minimum order 100 ct / 20 g.
• cBN Powder HPHT-synthesized cubic boron nitride abrasive powder for use in resin, metal, and vitrified bonded grinding tools, with size bands optimized for rough and finish grinding.
• Diamond Sintered Body (PCD) Polycrystalline diamond (PCD) sintered blank used as a raw insert for cutting tools and wear-resistant components, offered in special shapes and grades.
• cBN Sintered Body (PcBN) Polycrystalline cBN (PcBN) sintered blank for high-speed precision machining of hardened steels, cast irons, and other difficult-to-cut materials.
• Special Sintered Body Custom-shaped and application-specific sintered diamond/cBN bodies tailored to customer specifications for specialized tooling and wear-part applications.
• Diamond Plate (CVD Diamond Substrate) Plate-form CVD diamond substrate material used as a heat sink or precision component substrate in electronics and semiconductor-related applications.
• Diamond Electrode Boron-doped diamond electrode supplied in cell/module form for water purification, ozone generation, and other electrochemical processes, with engineering/field support.
• Lab Grown Diamond Gem-quality synthetic diamond produced by Tomei for use in fine jewelry, sold to retail and jewelry-channel customers.
• Tsubu Diamond Memorial/keepsake lab-grown diamond product line offering personalized commemorative gem diamonds for individual consumers.
• QR Diamond Traceability-branded lab-grown diamond with an identifying QR code, marketed to consumers seeking verifiable provenance and authentication of synthetic gem diamonds.
• Ozone Water Generation System Application system using Tomei's boron-doped diamond electrodes to generate ozone water for sterilization and water-treatment uses, supplied as an integrated solution.

Quantifiable outcome

• GHG emissions reduced to 1/7th compared to mined diamonds
• +2 more outcomes

Segments3 records

Ideal customer profiles5 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Partnerships

Two partnerships are on record, tiered core and minor.

• University research laboratoriescoreStrategic or Co-development PartnerTomei Diamond collaborates with university research laboratories to develop new technologies, leveraging over 60 years of accumulated knowledge to solve difficult technical problems that field engineers would normally abandon. This partnership is used for developing new materials and applications including diamond electrodes and lab-grown diamond products.
• Manufacturing partner companies (tool manufacturers)minorOthersWhile Tomei Diamond is a materials manufacturer and does not produce tools itself, it introduces customers to partner tool manufacturers that it has business relationships with, enabling customers to source complete tool solutions.

Scale indicators5 records

Recent moves12 records

Expansion highlights5 records

Emerging players

• Diamond Foundry: U.S.-based CVD lab-grown diamond producer focused on jewelry and emerging electronics applications (diamond wafers). Comparable lab-grown diamond manufacturing capability using CVD, with similar ESG-driven positioning.
• NanoDiamond Products: Specialty manufacturer of detonation nanodiamonds and ultra-fine diamond powders for precision polishing, electronics, and biomedical applications. Overlaps with Tomei's nano-sized diamond powder line (MD/IRM products) in semiconductor and electronics polishing.
• WD Lab Grown Diamonds: Vertically integrated CVD lab-grown diamond producer focused on jewelry, with a U.S. manufacturing footprint. Comparable lab-grown diamond capability but with no significant industrial abrasive business.

Direct peers

• Hyperion Materials & Technologies: U.S.-based manufacturer of synthetic diamond and cBN powders, PCD/PcBN compacts, and cemented carbides serving precision machining, automotive, and stone/civil markets — the closest direct peer in product breadth and customer overlap.
• ILJIN Diamond: Korean synthetic diamond and cBN powder manufacturer with global distribution, serving the same industrial abrasive end-markets (semiconductors, automotive, stone). Comparable product set and Asian-manufacturer cost positioning.
• Sino-Crystal Diamond (Zhengzhou Sino-Crystal): China's largest synthetic diamond producer, offering industrial diamond powder, PCD, and CVD diamond. Direct competitor in commodity industrial diamond powder markets and a key driver of global pricing pressure.

Broad incumbents

• Sumitomo Electric Hardmetal: Japanese industrial materials and cutting tool maker offering cBN and diamond tooling products. Overlaps in cBN/PcBN sintered bodies and serves similar automotive and machinery customers, but as part of a much broader portfolio.
• Element Six: A De Beers group company and the global leader in synthetic industrial diamond and cBN materials, including PCD/PcBN products and CVD diamond. Directly comparable product portfolio (powders, sintered bodies, electrodes) but operates at vastly larger scale across multiple geographies.
• Sandvik Coromant: Global metal-cutting leader offering diamond and cBN tool materials as part of its broad tooling portfolio. Competes with Tomei-supplied materials at the downstream tool level and also sources similar abrasive inputs.
• Mitsubishi Materials: Japanese broad materials and tooling conglomerate with significant cBN and diamond tool offerings. Overlaps with Tomei customers in automotive and machining, but competes as part of a much wider product portfolio.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights7 records

Customer concentration

• Facebookfacebook.com/TOMEIDIAMOND
• LinkedInlinkedin.com/company/tomeidiamond

Compliance1 record

Revenue estimate

Valuation estimate

Number of profiles

Profiles1 record

Subsidiaries2 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Tomei Diamond