Jan and Paul,
 
No research, but a tiny bit of experience: I found a really lovely 6"
Lightning Whelk, Busycon contrarium (or whatever you are calling it these
days) in a shallow mangrove-lined lagoon down in one of the islands off SW
Florida about 20 years ago.  It was purest white, flushed inside with a
lovely violet shade, and the operc was very pale.  The violet has faded to
nearly pure white, even though the shell was always wrapped in tissue and
in a box out of the light.  So it happens in other families besides the
Buccinidae.  But the lavender and violet tones in some of the Latiaxis and
Drupas in my collection have not faded much in as many years.
 
Lynn Scheu
 
 
>  Dear Jan;
>       The violet color fades rapidly- it is aparently an unstable pigment,
>as are many violet and blue-green pigments in nature - does anyone know of
>research into this topic??- it is quite a curiosity!!
>-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Ross Mayhew: Schooner Specimen Shells: http://www.schnr-specimen-shells.com.
>(902-876-2241) fax (902-479-1863).
>Snail Mail: P.O Box 20005, RPO Spryfield, Halifax, N.S.,Canada, B3R 2K9.
>"We Specialize in the unusual!"
>(and no, i REFUSE to inflict you with a clever quote, repaeated 50,000
>times!!")
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<