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Testo Drive 365 glass-like material which has similar optical properties to that of diamond. The fracture that is being filled must reach the surface of the diamond. Some clarity enhanced diamonds could have been laser drilled and then fracture filled. The biggest problem that this treatment presents is when a fracture filled clarity enhanced diamond comes into a jeweler's shop for some type of repair work. Heat from a torch https://pilpedia.com/testo-drive-365/