Day 455-Colonial Williamsburg Amethyst
Here is a second example of a water bottle that I consider to be Mulberry. Unfortunately, this water bottle is, like the previous one, not etched Blenko on the bottom. Mulberry was a catalog color in 1958 and at some point in 1958, Blenko started etching the base with Blenko.
Blog Update-November 30, 2013: I am now quite certain that this is the color that Blenko used to produce the Colonial Williamsburg Reproductions from 1936 to 1966. Mulberry is a lot more gray and a lot less vibrant.