Re: resale value - I'd say there are two main groups - collectors and practical users. Collectors buy for aesthetics, rarity, and name (they may occasionally use them, too, of course). Practical sharpeners care less for looks, names, etc, and just want something that works. Most users here fall somewhere on that spectrum, but certainly a mix of each, haha. What I'm trying to say is, don't worry too much about resale value when buying a stone - there's likely someone somewhere looking for what you have. Given the fact that stone prices are increasing year over year, mainly because they're not a renewable resource in the normal context, etc, some of your stones may actually increase in value slightly, as long as you don't damage it or whatever. Exploring the Jnat club link posted earlier, you'll read about just what I'm talking about.
Stones for knives are typically broken into 3 main categories in grit value and use (it gets way more complicated for swords):
Ara-to - Coarsest stones meant for chip repair and bevel setting (in reality, synthetics have taken over in efficiency and practicality for these purposes). It's important to remember that there is no official organization that oversees all this, so you'll see people classify ara-to in grit anywhere from 120-600 or 800 to 120-1000, etc. Since I like the power of 10, I casually say around 1000 is the top limit, but it seems most people say 800. Examples of such stones would be a variety of Omura, coarser examples of Natsuya, iyoto and numata, but there aren't very many coarse stones out there, but a lot that fall into the 1000-2000 range (which is why I like to say ara-to end closer to 1000 - ara-to selection becomes very limited without including these, but this is just my opinion...)
Next is Naka-to. There are a lot of stones in this group and make up a good portion of a well rounded collection. Again, you'll find definitions of grit range from 800/1000-3k/5k, etc. Mainly 800-3k. These stones will be able to finish a lot of knives in one's kitchen, especially if one primarily uses softer steels since soft steel can't hold an edge that higher grit stones yield. These stones generally refine the edge bevel and put on a pre-finish edge (if you continue to go higher in grit), or finish the edge, but are not generally used for chip repair (would take forever). Examples of these stones would be: more traditional aizu, iyoto, numata, binsui, ikarashi, aoto (also today's 'aoto' - atagoyama monzento of different colors), some hakka, etc.
Shiage-to stones are the last stage. Let's say they range 3k+ (the sky is the limit). Because there are so many stones that fall within this range, I like to say shiage-to start at 5k (but again, that's JUST ME, and I'm probably going to get yelled at for thinking like this, haha), but I understand the lower limit. Not the biggest deal, as you'll begin to understand what 'fine' vs 'less fine' is like. Anyways, these stones are for imparting the final edge on your knife, and polishing. These are also the most expensive stones for a number of reasons - fine, hard stones, are at the bottom layers of mines (it helps to think of stone layers like they were different density liquids that have settled and compressed over millions of years - the heavier stuff settles to the bottom and gets further compacted by the weight of the other layers above it), and are harder to get to (generally - you have to remember that the ground moves and forces are at battle, etc, etc). They're also heavy, so transporting them costs more. A worker can only carry so many at one time, companies charge by weight, etc. They also usually contain the patterns that everyone loves - karasu, renge, etc, and colors, kiita, shiro, etc, in their most glorious examples. People could argue all day about whether these attributes are helpful or not, but it doesn't really matter because they cost more simply because of the market says they cost more. Examples of such stones are suita (ohira, okudo, etc), most tomae, uchigumori, etc.
Things are also relative. If you wanted to finish with some teeth, you'd finish at a coarser stone, but you wouldn't call it a shiage-to or awase-do (fine stone). You can finish at whatever you want, and that last stone is simply your finishing stone. Therefore, coarser is also relative, as is finer. Use the ara-to, naka-to, and shiage-to grit breakdown as a guide. Once you collect a number of stones, these categories will become clearer overtime, and things will become easier to comprehend (usually, with some major caveats, haha, trust me). If I were to mention to someone to use a 'coarse' stone, it would like be in the 1-2ish range, maybe even a toothy 3k aoto. Sorry to say, but this whole thing isn't perfectly linear and clear.
Hope this helps.
irate1:
