These water bottles show up on auction sites on a regular basis as Blenko and they most definitely are not. My examples have paper labels on the bottom that say CIRCLE GLASS LLC Made in China. The surface of the glass is reminiscent of the pattern of hammered copper. The mouth is much larger than the one on a Blenko water bottle.
These are the only four colors that I have seen.
UPDATE: July 18, 2012:A red example was purchased on Ebay for approximately $35.00 including shipping. Within days, the seller listed another in red. I will attempt to obtain a photo of the red example. (I was not the buyer.)
Blog Update-November 23, 2013 While at Blenko in October of this year, I was shown an example with an Anchor-Hocking label on the bottom. I do not know if Anchor-Hocking is making this water bottle or is just importing the Chinese made product.