I sent two blades (that I bought from Jeffers labeled as ceramic blades) along with several steel ones to Fort Worth Shaver last month. They called me saying they could not sharpened the two "ceramic" because they were plastic even though they appeared to be ceramic.
Said they could replace them with ceramic blades for $10.00 and they would be able to sharpen them in the future.
I decided to do that as it is cheaper than buying a new blade. In the future I will buy regular Oster blades to start with then I will know what I am getting.