Also natural stones have a random grit size that gives a long lasting edge. Basically the random grits create varying sizes of micro-serration in the blade that wear down at a different rate, therefore longer edge retention. Whether this is true or not we really like natural stone, especially for sharpening tradition single bevel Japanese knives. Use natural stones with water – it’s far cheaper than sake.
Diamond plates are available in various plate sizes (from credit card to bench plate size) and grades of grit. A coarser grit is used to remove larger amounts of metal more rapidly, such as when forming an edge or restoring a damaged edge. A finer grit is used to remove the scratches of larger grits and to refine an edge. There are two-sided plates with each side coated with a different grit.
Made in the USA means a lot! It sharpens quickly, whether you need to remove a lot or just a "tune up" on the blade edges. Because it's manufactured flat, it is excellent for planer blades and chisels. The ability to sharpen dry or with only water creates less of a mess than other types of sharpening stones. The no-hassle guarantee is a definite plus, though I would be surprised if you ever needed it.
Now that you're holding the handle and the blade is in position, gently apply some pressure to the belly of the blade with your left hand fingers – "roughly the amount of pressure to semi depress a sponge," says Warner. Starting at the tip, glide the blade up and down the stone – around five strokes up and down is a good number. Then move to the middle – five more strokes. Finally five strokes up and down on the heel.
However, due to limited natural deposits and extensive quarrying over the centuries, true, high quality, Japanese water stones are now few and far between and are very expensive. Thus, various companies are now producing synthetic Japanese Water Stones which generally have a more consistent composition and grit size than natural stones as well as often begin somewhat harder and thus, lasting a bit longer; not to mention being cheaper to purchase.
It helps you get the knack for a consistently correct angle BUT the idea falls apart a bit when it comes to the curve and taper part of the knife and if your knife has an excessively narrow (slicer/boner) or wide (cleaver) width. It will also mark up the sides of your knife which may bother some who are obsessed with the cosmetic appearance of their $150+ Japanese knives--I could care less.
In addition, the most prized of the natural Japanese Water Stones are quarried in the Narutaki District north of Kyoto, Japan and are commonly available as either bench stones or pocket stones in grits ranging from 120 to 12,000. On the other hand, synthetic water stones are made from Aluminum Oxide and commonly available as either bench stones or pocket stones as well in grits ranging from 220 to 8,000 and, although this is the same abrasive material used to make India Oil Stones, the difference between the two is that the binder that holds the abrasive together enables Water Stones to be much softer than India Oil Stones which, in turn, promotes faster cutting because the worn abrasive material breaks away more quickly and is replaced with fresh, sharp, abrasive material more quickly. In addition, because water stones do not become glazed or loaded with swarf like oil stones can, new abrasive particles are constantly exposed as the stone wears so it continues to cut consistently. Plus, they can be lubricated effectively with water (rather than oil which can ruin some water stones) which combines with the fine particles of abrasive from the surface of the stone to form a slurry which polishes the bevel as the stone cuts. However, it should also be noted that Water Stones do become uneven significantly faster than other types of whetstones although, their softness does make them easier to true again.