Delia,
Thank you so much for for efforts!
I can't see anything that looks like part of a label. There might be something further inside, but I don't want to open the jar.
Any help, from additional experts, would be greatly appreciated. I'm in no hurry at all. It's not bothering anyone by sitting on its shelf.

Thanks again,
Bob Mason

Hi Bob,
I wanted to check in and give you an update - my colleague has never seen one of these before. We're trying to track down people who were connected with Mattel to confirm if this was a prototype.
More later, hopefully soon!
Delia

Delia,

Thanks for the update.

Have a great day,

Bob Mason

Hi Bob,
I'm sorry it's taken me so long to get back to you, and I regret I haven't been able to fully resolve this but I've spoken with several people - none who were working at either Coleco or Mattel when this would have been made - and the general consensus is that it is a very limited edition "Coleslaw Doll" as it was advertised and not a prototype. Everyone was very interested in seeing it but no-one could tell me where I could find another one or provide a reference to a comparable example, etc.
As to giving it a value, that's also a bit complicated as there aren't any others that have come to market that anyone can find. Currently, Cabbage Patch dolls - even those signed by Xavier Roberts are selling for less than $100 at auction (prices on eBay are unreliable...people put whatever price they want on things and hope they find someone willing to pay that price). My colleagues and I discussed ideal values - the number everyone seemed to like was $400-600, which is what I've priced this at here. It's high enough to support the idea that this is a rare/unusual thing without being so high as to be unrealistic in terms of selling it. If you'd kept the original packaging, it would have a value of $800-1,200.
Thanks again for letting me have a bit more time to research this.
Delia