Sumiseki Holdings, Inc. engages in the manufacture and sale of coal products, artificial diamonds, and crushed stones. Its operations are carried out through the following segments: Coal, New Materials, and Quarry. The Coal segment handles the purchase and sale of coal. The New Materials segment manufactures and sells synthetic diamonds, and artificial diamonds for industrial use. The Quarry segment covers the collection, processing and sale of crushed stones. The company was founded on October 1, 2008 and is headquartered in Tokyo, Japan.