ceramic knives with the S G

[tgbto]

[...] due to the much higher polishing process  i have found the resulting edges to be less chippy [...]

From a physical standpoint, "chippiness" will depend on intrinsic properties of the material used, and the thickness of said material.

So if the blade has a thinner apex, it will be more prone to chipping, not less. However, your particular sharpening process and methods may result in a geometry that will both be more resistant to chipping (so a thicker apex), but that might feel sharper as explained in the scienceofsharp article.

[kwakster]

The intrinsic properties & the thickness of the ceramic material most certainly play important parts in useful edge life, but the degree of edge polishing also has proven to be very important yet often overlooked.
Scratches in a ceramic knife apex work as crack initiators, and when those scratches get smaller and smaller due to progressively finer polishing the apex becomes more resistant to chipping as well as keener.
The Forever white ceramic knife in the first two clips has an apex of ~25 degrees inclusive, and it could reverse whittle a chest hair, meaning from hair root to hair point, which is noticeably more difficult than from hair point to hair root.

There are also huge differences in ceramic knives from different manufacturers, and i have found many cheaper ones to be simply not worthy of resharpening.
The two best brands i've encountered so far are made by the Japanese companies Forever and Kyocera (in that order)

According to reports there seems to exist an ever higher quality ceramic knife material, which is made by Swiss company Rahven, but i have not been able to get my hands on one.
Not only does Rahven offer various kitchen knives under their own name, recently they also manufactured a so called "mule" model for Spyderco.

[tgbto]

As a general comment, if you polish a scratch, you're essentially flattening the ridges, but the bottom of the scratch remains as it is. So there shouldn't be an impact on fissuration mechanisms.

That being said, I don't think these mesoscopic cavities are what drives the chippiness. As mentioned in the article :

the blade consistently separates along grain boundaries resulting in sub-micron roughness

.

The characteristic dimension of the grain boundaries is several orders of magnitude smaller than the typical dimension of your "scratches" (which aren't scratches as much as actual chips, really), so the local constraint is several orders of magnitude higher along those boundaries (as cavity size and constraint are inversely proportional).
 
It really is what happens on a sub-micron scale that matters for fracturation initiation, and it's not affected by polishing.

The thickness on the other hand plays a huge role in that it determines how far a fissure has to propagate before the material breaks.

[kwakster]

Here's a link to the review on another forum of that Forever white ceramic knife i did years ago.
In it there are quite a few close-up pictures of the edge, among which several made with a USB-camera.

https://www.talkblade.info/viewtopic.php?f=2&t=24961&sid=db2731afeb2f0f27e9de84ee5ce1c77b

My invention of using fine diamond compounds together with certain types of oil on a naked Paper Wheel has been a game changer in sharpening ceramic knife edges, and a bit later also for steel knife edges.
When i explained my process on the Australian blade forum Vadim Kraichuck was one of the first knife sharpeners who adopted it.

[tgbto]

Your edges look nice.

I was just commenting on this sentence :

Scratches in a ceramic knife apex work as crack initiators, and when those scratches get smaller and smaller due to progressively finer polishing the apex becomes more resistant to chipping as well as keener.

If anything having "smaller scratches" will increase the mechanical constraint due to local traction forces, so if this was the driving mechanism, the edge would be more prone to chipping.

But I think what's at play here is that higher RMS roughness along the edge results in areas where there is little material left at the apex, and these fragile areas will break off easily.

Back to the post of the OP, the SG is indeed much too coarse for it being any good on ceramic knives : it will tear off huge chips due not to the hardness of aluminium oxide, but to lateral stress on the blade at a scale corresponding to the rougness of the stone itself.

[3D Anvil]

I can imagine that the SG, graded fine, could be a good place to start for grinding out larger chips.  But from there I think it would best to move on to higher grits.  I wonder if the Japanese Wheel would improve the SG result?  After that 4000 grit finish, six, three, and one micron stropping could be the ticket.  Or sharpening on 8000+ bench stones and then stropping. 

Anyway, I'll have a go at it when the factory edge gets chippy enough (and it seems to chip quickly with my wife/chef behind the wheel).

[tgbto]

But from there I think it would best to move on to higher grits.  I wonder if the Japanese Wheel would improve the SG result?

My .02: you'll shape the wheel long before you notice any significant difference in the finish of the ceramic blade.

As explained in the scienceofsharp article, you need a hard support with fine particles to sub-microchip the edge in a consistent fashion.

[Ken S]

I think if I ever need to sharpen a ceramic knife, I will stick with the DF wheel.

Ken

[tgbto]

I think if I ever need to sharpen a ceramic knife, I will stick with the DF wheel.

Ken, based on the findings of the scienceofsharp article, the finer the grit the better, so you should probably go for the DE wheel.

[Ken S]

Thanks, I will keepthatin mind.
Ken