| 1927 |
Establishes Sumitomo Coal Mining Co., Ltd. |
| 1987 |
Starts synthesis experiment of poly-crystalline diamond powders with Tokyo Institute of Technology. |
| 1989 |
Starts production experiment at our old coal mining sites in Akabira, Hokkaido. |
| 1991 |
Starts commercial production and sales by Izumi Diamonds Ltd, 100% subsidiary of Sumitomo Coal Mining Ltd. |
| 1997 |
Changes Izumi Technology Co., Ltd by the merger with another 3 manufacturing subsidiaries to extend our business field boundlessly. |
| 2000 |
Transfers sales dept. of diamond business partly into Sumitomo Coal Mining Co., Ltd.
Increases production of the fine sizes for great demand from the Magnetic Head and HD fields. |
| 2002 |
Expands the grading facilities for increasing a great demand from the Optics fields, especially Sapphire glasses. |
| 2003 |
Transfers all department of diamond business into New Material & Processing Div., Sumitomo Coal Mining Co., Ltd.
Became one of main business into Sumitomo Coal Mining Co., Ltd. |
