My $5.00 ceramic knife has lost it's razor edge after about 6 months of daily use. I like the knife and will purchase more ceramic knives andget better quality. But, for $5 it was a good introduction. I looked on the web and attempted to sharpen it with the fine/coarse "Smith's" diamond sharpener I have that is about 1" x 4" and has served me well. I only worked on the knife for a few minutes and since I didn't know what I was doing and afraid of doing damage, I stopped. What's the method to correctly sharpen ceramic knives?