Full Idea
My view is that the concepts of both the Earth person and the Twin Earth person refer to BOTH forms of diamonds or water (H2O and XYZ).
Gist of Idea
If 'water' has narrow content, it refers to both H2O and XYZ
Source
Gabriel M.A. Segal (A Slim Book about Narrow Content [2000], 1.7)
Book Reference
Segal,Gabriel M.A.: 'A Slim Book about Narrow Content' [MIT 2000], p.19
A Reaction
Fair enough, though that seems to imply that my current concepts may actually refer to all sorts of items of which I am currently unaware. But that may be so.