This is what we use in our GC lab to cut capillary tubing. Made from hard ceramic, it is easy to use. Simply pull one smooth edge of the scribe (tilted about 45° degrees) across the column to lightly score the fused silica - bend the column opposite the score and the column separates cleanly. Perfect for removing the first meter of older columns to rejuvenate their performance or to clean-up the tip of the column after threading ferrules over it.