Thanks for the further information and the photos.
I'm afraid I can't help much more. For me even with the close up photos it's very hard to tell how it was made unless you have it in your hand.
I cannot tell how this might have been made as I don't have that experience, but in my humble opinion, it looks as though it has been cased in three layers, white, cased in pale pink, cased in dark pink. In terms of the process, it might be possible that the outline of the decoration all over was achieved by
- acid etching the background areas back to white leaving a dark pink pattern.
- Then polishing the dark pink pattern all over
- Then carving the dark pink off in areas back to the pale pink (I'm unsure whether cameo makers would work on an already polished surface though)
- Leaving the dark pink highlights glossy
and showing the pale pink as an unpolished/cut surface?
and showing the white as a mattish acid etched surface?
Did you notice whether the white and pale pink were as shiny as the dark pink highlights btw?
I think it is a beautiful piece and if it has been hand carved as well, you need specialist help to identify it so it sells at the right price. Actually either way I think you need specialist help for it
I'm sorry I can't be more helpful. Hopefully Christine might have found more information for you.
I will continue to look for any examples that might help and come back if I find any.
Would you please let us know if The Corning Museum comes up with any id for it? I'd love to know who made it. I still think the large polished pontil mark and the colour might point to Stevens and Williams, but that is just a guess.