Ask A Scientist Physics Archive

name         Stephanie E.
status       other
age          30s

Question -   I thought that precious metals were not supposed to be
magnetic (ie gold, silver and platinum). Yet I took what I thought to be
a platinum engagement ring and held towards a magnet and it stuck. Does
this mean that the metal is not pure? Or does it have something to do
with the diamond?
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Regarding the ring, diamond is not magnetic or paramagnetic. The diamond
could never stick to a magnet. The precious metals are also not magnetic,
but they are soft and could not be fashioned into a ring unless other metals
are used. Clearly your platinum ring has had ferrous material added to it.
Ask the vendor, if the ring is platinum coated and/or which metals were used
in making the ring.

 Dr. Harold Myron
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Platinum is actually paramagnetic.  That means that it can become slightly
magnetic in a magnetic field (such as near a permanent magnet), but its
magnetism disappears when the magnetic field is removed.  So, platinum will
be weakly attracted to a magnet.  Is this effect large enough to notice with
a ring-sized hunk of platinum and an ordinary magnet?   I do not know.

Diamonds, on the other hand, are diamagnetic, which means that they will NOT
be attracted to a magnet.  It is possible that the prongs on the ring that
hold the diamond in place may be attracted to a magnet, but the diamond
certainly will not be.

Richard E. Barrans Jr., Ph.D.
Director of Academic Programs
PG Research Foundation, Darien, Illinois
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Stephanie,

You are correct. The metals you mentioned are not attracted to a magnet.
Likewise for the diamond -- also not attracted to a magnet. If your ring is
attracted to a magnet it must contain iron, nickel, or cobalt somewhere in
the metal that comprises the ring or the stone's mounting base. Touch the
magnet to different parts of the ring to see if certain areas are more
strongly attracted.

Regards,
ProfHoff 466
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I hope you did not pay too much for this ring. Neither platinum, nor
diamond is magnetic. It would appear that some metal like nickel or iron was
plated with platinum. You should have the ring examined by a certified
gemologist.

Vince Calder
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