... ,SGS Testing 4,hardness second to diamond Ceramic Knife – High Density ZirconiaModel: 3", 4", 5.5", 6.5", ceramic knife eriesBlade Material: zirconium dioxide (ZrO2 ... availableHandle Material: ABS+TPR handleSize Available: 3", 4", 5.5", 6.5"Features: Our ceramic knives are made of ZrO2, the hardness would close ... time and provide better services to you. Thank you. 6.5 inch ceramic knifes