That rings a bell. I think it was. There definitely was something about it having an interchangeable feature - ie being able to swap out stones to replace with other stones.
If it was the Vladimir then it was a massively cheeky request as it's so often worn by the Queen.
The only other one I can think of with emeralds that can be added is the Dehli Durbar, but that's massive and worn by Camilla
The only other potential emerald one I can think of, that would be unseen for years and have potentially unknown emeralds, could be Queen Victoria's emerald one that Prince Albert designed, but I don't think that is in the main royal collection anymore.