Ross (in Reply #5) is basically correct, but with a few adjustments. I suggest the piece was made by Tina Cooper around the time of the breakup of her partnership with Mark Galton, called Martini Glass. That dates it to about 1995-1996.
Martini Glass operated between 1990 and 1995 and moved around several towns in the hinterland of the Sunshine Coast north of Brisbane (Mapleton, Buderim, etc.). After the partnership ended, Mark and Tina both continued as glass artists, with Mark moving to Burrill Lake on the NSW south coast and Tina staying in the Sunshine Coast area (working from Eumundi, Yandina and Noosaville). Tina now has an extensive business with a prominent web site, while Mark’s own web site has disappeared, although he is mentioned on several tourist web sites.
Most but not all of Mark Galton’s output is signed. Most but not all of Tina Cooper’s output is unsigned. Indeed, much of the large volume of output they produced jointly is signed, but by no means all. The signing was mostly (but not always) done by Mark. He has by far the better handwriting, except when he is exhausted from surfing or otherwise tired and emotional.
The attributions on Ross’s four examples are shaky. The first item, which he attributes to Colin Heaney is in fact a Martini product. The first photo below shows a nearly identical item 12.5cm high by 9cm diameter and inscribed “Martini Australia 1992”.
The second and fourth of Ross’s examples are by Mark Galton after the dissolution of Martini Glass. The evidence on item 2 is the photo of the signature that Ross himself provides on Glass Gallery, which says “Mark Galton”. This is an example of Mark’s handwriting at its worst, although the similarities to other examples of his signature are obvious. Ross’s item 4 is very similar to an item on ebay.au a few months ago, shown in the second picture below. That one was inscribed “Mark Galton Australia 2003”.
The third photo below shows detail from a Tina Cooper product from a few years after the break up of the partnership. It is clearly more mature than selina’s piece that started this thread and is acid treated. This item is unsigned, but a nearly identical piece is scrawled “Tina Cooper 1998”. Hence my dating of selina’s piece in the middle 1990s.
Trevor