A niece of mine is an avid amateur Chef (but not yet a knife
afi), and this black ceramic knife
(a rebranded Kyocera) is one of her favorites in the kitchen, as due to the tougher blade material the edges can be made thinner and thus the knife
cuts better than a white ceramic
Longtime use however (not always on a suitable cutting board) plus storing it unprotected in a drawer between a bunch of steel bladed knives had blunted the edge to a point next to unusable, complete with quite a lot of (micro) chips and a broken tip.
Removing the chips and setting the new bevel was done with a Tormek T7 fitted with an SB-250 Black
Silicon stone, refining & convexing with a Paper Wheel coated with 15 micron diamond compound, and semi-polishing with a second Paper Wheel coated with 6 micron diamond compound.
This is the knife
as it was when i received it.
(when you click the pictures 2 x you can see the chips clearly)
This is the knife
I reprofiled the rather bad factory edge to an ever so slight convex edge of +/- 25 degrees inclusive, and the sharpness is just hairwhittling (only towards the root, not to the point), and it easily slices single layer toiletpaper (torn apart 3-layered version)
(and a tomato of course)
Overall length: 11.0 inch (28,0 cm)
Blade length: 5.8 inch (14,8 cm)
Blade thickness: 1,84 mm
Blade type: black ceramic
Thickness behind the edge: 0,4 mmA black (HIP) blade is made out of a black zirconium oxide and offers extra durability.
This type of blade goes through an extra firing process called a "hot-isostatic press," creating a tighter weave between the ceramic molecules, thus creating a tougher blade.
The white ceramic blade is also made out of zirconium oxide, but does not go through this expensive sintering process.