I believe they are made using zirconia sand from Australia.  Take care while using them to cut on a ceramic plate.  If it knicks the glazing, the plate will fracture like glass.

I will only clean them in a dish washer.  I can’t imagine sticking my hand in a sink with soapy water and feeling around for one LOL.

A couple of years ago I wondered if the sharpness of a ceramic blade could be extended to a razor.  No corrosion issue of a steel blade.  A company does make one and I was an early adopter.  Big mistake.  

About the same time, the local library was having a science demonstration using liquid nitrogen.  I purchased a few bags of cheap disposable plastic razors and had them dunked into the liquid nitrogen.  Super cooling steel changes the grain structure (racing engine components are routinely treated this way for durability under extreme conditions).  Life of the blades is not infinite, but definitely extended.  I am still using them.

A dollar bill will shrink to the size of a postage stamp once placed in liquid nitrogen.  It retains the size when removed.