A good vintage Genuine Thuringian water hone razor stone.

This dark blue/grey stone is 4⁷/₈ inches (124mm) long by 1" (26mm) wide and ⁵/₈" (16mm) deep.

The top surface is smooth and flat with only a few tiny marks and a chip to one corner, please see close-up images.

The base shows remains of the original glue indicating that it was, as is typical, fixed in a hinged lidded wooden box.