Nakayama Maruka Asagi
Great things do sometimes come in small packages. Once a full size stone that took a fall, this remnant carries on like a champ. Measuring just about 3x5" - it's very hard - with good speed and lovely feedback. There is some non-invasive Goma on the top, and the Maruka stamp can be seen on the short end in the foreground.
This stone can be seen in-action here.
Dimensions: 4.9 x 3.0 x 0.75" / 125 x 78 x 22 mm
Weight: 17.8 oz / 504 g