This bottle is signed JS for Julio Santos. That information was included when the OP listed the item for sale on ebay, so this information is for other GMB readers.
Julio Santos is a giant of Australian studio glass. Born in Portugal, he was apprenticed in the glass industry there at 12 years of age. He came to Australia in 1968 and worked at Leonora Glass (Philips Lighting Industries) in Newcastle and later lectured in glass at the University of Newcastle 1976-78 and CIT now Monash University, Caulfield, 1978-82. He then operated his own studio in Tomago (just across the Hunter River from Newcastle) for another 25 years or so. His output was prodigious at all levels: exhibition art (often in collaborations), decorative and novelty items, and utilitarian household wares such as wine glasses and decanters. His last major exhibition (as far as I'm aware) was in 2010, although he was still working until a few years ago.
I can't find a photo of a closely similar item to the one in question, but here are three photos which show different aspects: (1) the general shape, (2) delicate twisted canework, and (3) his signature in which the JS looks almost like SS.