I know, I love that site. I've been on it many, many times.
On the Pottery and Glass Board Forum through eBay, there is a girl by the name of "Blenko loves Blenko" (aka Tammy) who, I believe, works for Blenko. She is the absolute expert and can answer this question in a New York minute....

She's very helpful and nice.
If it isn't Blenko, it may be Bischoff or

(I can't think of the names I'm looking for....) but if you do post over on that board, put Blenko in the title to be sure she looks at the post. She can, in all likelihood, give you the answer you are looking for...even if it's not Blenko.
Kate