Information on Tomei Diamond Company
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Company name

Tomei Diamond Co.,Ltd






Headquarters and
Sales department
Akasaka-Mitsuke Kitayama 8F
9-18 Akasaka3, Minato-ku,Tokyo 107-0052,JAPAN

TEL +81-3-3585-7981  FAX+81-3-3585-3282
OYAMA Plant 5-1 Joto4, Oyama City,Tothigi,JAPAN
TEL +81-285-22-5821  FAX+81-285-22-5827

Purpose of Establishment

Production, processing and sale of diamond products for industrial and jewelry applications


100 million yen

Main correspondent banks

Mizuho Bank,
The Bank of Tokyo-Mitsubishi UFJ,
The Bank of Yokohama,
The Shoko Chukin Bank,
The Ashikaga Bank

Settling day

March 31

Head count


[OYAMA Plant]

Ground 25,500m2
Plant 15,400m2

History of the Group Companies of TOMEI DIAMOND

April,1953 We made Ishizuka research institute.
December,1956 IRI succeeded in industrialization of metal zirconium.
April,1960 IRI succeeded in composition of the diamond first in Japan.
May, 1961 We succeeded in the synthesis of the diamond for the first time in Japan.


We began commercial production of synthetic diamond.


We succeeded in upsizing of the diamond synthesizer.
We contributed to stable supply of the synthetic diamond , when Japan was enjoying a period of rapid economic growth and consumption of synthetic diamond increased.


We made a Tomei Diamond Industry.
We transferred the production right and sale right of the synthetic diamond to Tomei Diamond Industry.


We made Osaka Tomei Diamond and improve the sales of West Japan


We transferred the production base of the synthetic diamond from Tomei Diamond Industry to Tomei Diamond to improve export and domestic sale.
We made Tomei Diamond Industry the sale company.


We made TOMEI CORPORATION OF AMERICA in State of New Jersey to deal with the demand of the American market.

April,2004 We separated export sector from Tomei Diamond Industry and transferred it to Tomei Diamond International.
December,2009 The "Tomei Diamond Industry " "Osaka Tomei Diamond " "Tomei Diamond " "Tomei Diamond International"4 company merged.
The company name was unified into "Tomei Diamond ."
April,2010 The company name which Ishizuka research institute and Tomei Diamond merged was set to Tomei Diamond .
May, 2012 Application of the development-grants system which Tokyo is carrying out was received.


Access:3 minutes walk from Akasaka-mitsuke Station

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[OYAMA Plant]

Access:30 minutes walk from the east entrance to JR Oyama Station
( 10 minutes by taxi )

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