This tool is a Matting Background Stamp and is number E386. The tool measures a little over 3/8" in diameter. Stamped on this tool is "E386" and "Craft Japan". This is a great stamp that produces a nice impression.
Craft and Co. of Japan produce fine quality leather stamping tools in unique designs along with some of the basics. Since their establishment in 1959, they have continued to develop tools in their own factory and have laid the foundation for the leathercraft industry in Japan.