How do I shop for and start using natural stones? –Charlie C.
This is an interesting and also enormously complex topic. I’m bound to fail to express what I know in a digestible form. Before we can get into how to begin, it’s worth going over why natural stones might be worth your time (and why maybe not).
In brief, natural stones cut and feel different than synthetic stones. Most importantly, the grit in natural stones can break down and become finer as it is used, giving these stones a lot of effective grit range compared to man-made stones. Secondarily, that grit range (mixed in the stone, and also changing constantly) means natural stones can leave different finishes that are considered beautiful (either hazy, or highlighting different patterns in iron through interesting corrosion). Some believe natural stone edges, because of the grit break down of scratches, various hardness levels of different particles, and in general rounder shaped particles, can create edges that can last than as with synthetic stones.
(The shape of scratches is a topic of discussion between different types of stones like diamond, manmade and natural stones, as is the scratch direction. Different types of scratches in different directions can give you different types of edges. This is a topic for another day.)
These stones are sometimes more or less hard, resulting in different types of abrasion and even the shape of the edge. Harder stones also end up more dish resistant than many man made stones, and some times these stones can be scratchy unless used with a lot of slurry, meaning a bit of prep work is necessary in building that mix of water, iron, steel and stone; related, some less expensive stones also might have strong lines of impurities, which can scratch your blades.