To the OP: Are you shopping for stones? If so, we can probably make some recommendations based on your needs. Budget, knife blade steels, knife types, etc will all influence the decision.
On the other hand, if you're just trying to get an overview, David's answer is a VERY good starting point.
Tell us more about what you're trying to accomplish and we can probably help.
Brian.
Yes, David's response was pretty much in line with what I was looking for. Thanks David.
As for what I was trying to accomplish, only trying to get a topic going that lists pros and cons of the different options for sharpening. Did not have much luck using the site search (why does the site not allow people to add tags to the posts? makes the search function work much better on other sites).
Like what someone said; whatever can dull, can also sharpen. But each has strengths and weakness.
Would kind of like to see a chart that summarize what David said into a chart form, with others added later. Something like this:
[table="width: 500"]
[tr]
[td]type[/td]
[td]pros[/td]
[td]cons[/td]
[/tr]
[tr]
[td]Diamond[/td]
[td]quick, stays flatter longer, does not require lubrication[/td]
[td]most expensive on average, less forgiving, require light touch, can't polish as well[/td]
[/tr]
[tr]
[td]Natural/Arkansas[/td]
[td] less expensive?, more forgiving of over pressure, [/td]
[td]slow cutting, not as effective with harder steels, should lubricate, can be messy [/td]
[/tr][tr]
[td]Ceramic[/td]
[td]cost? good for fine polishing/refining, very hard [/td]
[td]cost? unforgiving or hard pressure, clog up easily, require more freq cleaning, must have feather touch for best results[/td]
[/tr][tr]
[td]man made / synthetic [/td]
[td]Cost? SiC are forgiving, wet/dry, AlOx [/td]
[td]Cost? AlOx messy oil, glazing if not lubricated [/td]
[/tr]
[tr]
[td]waterstones[/td]
[td]Cost? forgiving? touch? polishing? [/td]
[td]Cost? messy, etc [/td]
[/tr]
[/table]
If people on this site could agree, it might be good for someone to make a final chart at some point and create a sticky for newbies like me to get a quick comparison of the different options.