Tungsten rings can be removed by cracking them off with a pair of
vise-grip pliers. Although the material is very hard it is also very
brittle and will break under force. This is the same technique used
to remove ceramic rings that are stuck.
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Titanium rings, even the aerospace alloy of 6/4 Titanium (also
called grade-5), can easily be cut through with a Beaver style ring
cutter, even if equipped with a simple HSS (high-speed steel) blade.
I have cut several of my rings for demonstration purposes with these
ring cutters in less than 20 seconds. It is convenient to dismiss
these rings as being dangerous, but it really is not the case, and I
find that I have to fight this battle over and over.
Daniel J. Statman, Statman Designs