Depends entirely what it is made from. Does it have any metal markings? Very hard to tell from pictures but it does not look like gold to me - it may be a base metal with plating. To be honest it looks like badly plated brass to me, but I am only guessing from the photo. The cabochon looks like a member of the agate family, possibly carnelian. If it is not precious metal (and if it was it would definitely have a mark), and if it was not Australian, or did not have the maker's mark, I would be guessing just an antique costume brooch, $30. However because of the W Kerr mark you may well find extra interest from Australiana collectors. As I tried to hint in my first resposnse, I do not think this is of sufficient quality to be made by Kerr or his firm; I think they just added the mark as retailers.