Tsubota Pearl Hard Edge Clear Lighter - SilverPolycarbonate, steel, and cotton composition The model was introduced in 2005. It retains the clean economy of form of the original Hard edge, and adds a dimensional, ridged design to the casing. The geometric pattern is achieved through a method called diamond cut in which patterns are made with a diamond tipped engraving bit. We took the unusual, if inefficient, approach of employing this technique used for jewelry and the ornamentation of metal,