Radiohalos were first reported in diamonds more than a decade ago. Since that time little work has been done to locate other radiohalo-bearing diamonds, to explain the origin of the radiohalos, or evaluate their significance. We conducted a search for such diamonds secured from a variety of sources and identified radiohalos containing one, three and four rings, as well as strange features in the form of twisted crystalline “tubes.” New data suggest a radiohalo annealing temperature in diamond above 620ºC. We offer an explanation for the radiohalos and for the “tubes” in these diamonds in terms of a hydrothermal fluid transport model for Po radiohalo formation.
