O-Ha! Magnet = Elektrostein (98 x 30 x 10mm)

Size: 98 x 30 x 10mm weight: 80gr.
Density: xxgr./cm³ / Estimated grit size: very fine <12k
Usage: only with water, never use oil!
Color: green-grey, dark-grey, sometimes going in brown, mottled structure with black, blue, rose or green coloration
Other names:
mottled Thuringian, Schwedenstein, Swedenstein
Supplier/Distributor:
Otto Hunger, Elsterberg (Sachsen)

Chinese Water Hone C12K (200 x 50 x 20mm)

Size: 200 x 50 x 20mm weight: 647gr.
Density: xxgr./cm³ / Estimated grit size: very fine <12k
Usage: with water
Color: light-grey to grey-green, sometimes orange lines or inclusions
Other names:
Chinese River Hone, C12K, Kajima, PHIG, Chinese Pulpstone
Supplier/Distributor:
actually there seems to be a lot of sellers and a lot of re-branded stones around

HGH Haida Gwaii Hone (240 x 60 x 28mm)

Size: 240 x 60 x 28mm weight: 1110gr.
Density: xxgr./cm³ / Estimated grit size: ultra fine > 12k
Usage: with water, glycerine or oil
Color:  grey-green with dark-blue and white inclusions
Rockhound:
Shaun aka RezDog

Enat light-brown by Ekretz (170 x 64 x 16mm)

Size: 170 x 64 x 16mm weight: 484gr.
Density: xxgr./cm³ / Estimated grit size: very fine < 12k
Usage: with water, glycerine or oil
Color:  beige to light-brown with visible inclusions
Rockhound:
Ekretz