You guys are wonderful! Thank you for your responses!!
Connie, I have been searching on the net for an example of a Libbey mark with a cursive L that looks like the one on the bottle and stopper but I haven't found anything yet. I'll still explore that avenue, though.
First, I began my search looking for glass patterns of various makers that also have used the Greek key design..there's lots..
Then, I looked for examples of the greek key design used with the little cut dots or ovals. Finally, I looked for makers that incorporate most or all of the design elements found on the bottle, paying special attention to the wave design, in their pieces.
I discovered the beautiful craftsmanship of Hawkes glass and I was kind of thinking that this bottle may be his or a maker during the same era with the same style??
I just don't know. Does it matter? I guess not but I just love this bottle. It's so light and fragile. I want to be able to attribute it to someone. If it's a cruet, I'd really love to find a match for it. You guys are great!! Thank you again for your responses.