I've collected several red, rusty, Cyp spadicea from a wreck called the
Olympic 3 miles outside of Los Angeles Harbor. I also collected a rusty
mappa from a wreck in the Solomons and a rusty robertsi from a wrecked steel
shrimp boat in Baltra Harbor, Galapogos. All these specimens are very
glossy.  The rusty red color appears to be in the outer glaze. I can see an
area by the  syphon end on the mappa where the normal color shows through.
Hope these observations are of interest.
 
Paul Kanner
Los Angeles, Ca.