obsidian is'nt the sharpest edge--the diamond knife is. diamond knives are used to cut extremely thin tissue samples since even smaller lasers burn the real thin sections that are needed for microscopic study. obsidian was given up in favor for eye surgery since lasers could cut better & thinner. as mentioned science is'nt your strong shirt. please 123456 discuss something you understand so other members may be able to contribute. we are'nt impressed with your shallow science knowledge.---cranky72
