Index Home About Blog
From: B. Harris)
Subject: Re: Radiation & Jewelry Question
Date: Wed, 10 Dec 1997

In <66knha$l3p@clam.Hi.COM> wright@nospam.clam (David Wright) writes:

>In article <01bd04c9$ca4b1de0$de4318d0@irhsoicb>,
>GGlass <> wrote:
>>I recently found out that a stone ring I own, which I thought was an
>>alexandrite, is in fact some other stone that was treated with radiation
>>(don't know what type) to change its coloration to resemble an
>>Does any know if the stone retains any radiation from this treatment.
>This came up on sci.skeptic (I think it was) not long ago, but I don't
>recall if there was a definitive answer.  If you're concerned,
>however, I should think most college physics departments would have a
>Geiger counter.  And if you asked them nicely, they'd probably be able
>to pass your ring by it to check.

You can make a lot of crystals darken with gamma radiation.  Indeed,
even ordinary Pyrex beakers go brown if you zap them long enough.  The
process apparently generates color centers due to electrons which are
displaced by the radiation and can't get back to their "holes".  So you
get charges (positive and negative) stuck in the crystal, and these
absorb light.  But there is no residual radiation.

You can make the smoky appearance disappear again with shortwave UV,
which excites the electrons enough to return them to where they are
supposed to go (I once de-smoked a piece of radiated quartz this way,
by several weeks of nightly close exposure to a germiacidal UV lamp in
a bacterial hood).  Heating will also clear radiated crystals, if you
can heat crystals in such a way as not to cause thermal or oxidative

                                     Steve Harris, M.D.

Index Home About Blog