In article , "Leo Lichtman" wrote:

"Leon" wrote: Vivid purple turned brown when turning and sanding a
pen..... what kind of
acid are you using to bring back the pruple?
^^^^^^^^^^^^^^^^^^^^^^^
Purple heart is brown when it's cut or turned, but the color returns to the
surface on exposure to air. Exposure of the purple surface to sunlight will
turn it to an ugly brown. So, after turning a pen, just wait, and don't
leave it in the window.

Not in my experience -- I've observed the purple to be *intensified* by
sunlight.