Defining characteristics of Japanese kitchen knives are toughness (resistance to breaking), sharpness (smallest carbide and grain for smallest apex reduce force in cutting), edge life (an index for the length of time an edge will cut based on lack of edge rolling or chipping), edge quality (toothy with large carbides or refined with small carbides), and ease of sharpening (steel easily abrades in stone and forms a sharp edge). Although each steel has its own chemical and structural limits and characteristics, the heat treatment and processing can bring out traits both inherent to the steel and like its opposite counterparts.