Naniwa's Professional sharpening stone is absolutely sublime in terms of quality, ability and appearance. They make them in a material called White aluminum oxide, which is an incredibly hard material, which gives a lasting surface on the stone.
#5000 is really good to finish on if you have started with a really coarse stone, e.g. #240. It is also great for maintenance. A few strokes on both sides before use and your knife is like new.
Dimensions: L: 21 cm W: 7 cm H: 2 cm
Material: White aluminum oxide (WA)