Dazzled by Australia's colourful opals
Already legally defined as Australia's "National Gemstone", the country's precious opals are punting for a new international designation - that of Global Heritage Stone Resource.
This is a designation being devised by an international group of geologists. The intention is to name and define those stones deemed to have particular significance in human culture.
The initial concept was to recognise the classic rocks used in building construction, such as Portland stone, Carrara marble, Sydney sandstone, and granites like Norwegian larvikite.
But could it also include gemstones? Dr Barry Cooper, secretary of the Heritage Stone Task Group, discusses the merits of Australian precious opals with our correspondent Jonathan Amos.
08 May 2015