Greg
I think it will be helpful to understand that this is a copy of sorts of a traditional "ship's decanter" See the example at http://www.ross-simons.com/products/522615.html It is Waterford crystal and is cut glass. In your decanter, the pattern is molded not cut.
You are correct that the mold seam (stopping part way up the neck) on yours suggests an earlier bottle which along with the "straw lines" in the glass appear like an older hand blown bottle. However, many modern imitations are deliberately made to look old and this is a clear case. The uniformity of the glass thickness, the color and the manufacture details all yell, "Modern!"
Chris
