1851 The first gold rush in New South Wales. Sapphires are discovered in the Macquarie River and the Cudgegong River. It is reported that diamonds have been found in Reedy Creek and the Turon River near Bathurst. However there are doubts about this discovery as the stones may not have been correctly identified.
1851-1853  Topaz is found in the Cudgegong River and the Castlereagh River.
1853  The discovery of sapphires is reported at Broken Hill.
Hyalite is discovered near Cookabiandi in the Namoi River area. Hyalite is also know as Mullers glass. It is a transparent and colourless opal that looks like glass, although sometimes it is slightly coloured.
1860  The first confirmed discovery of diamonds - at the Macquarie River, Pyramul Creek and Caloola Creek.
Emerald discoveries are reported in several gold fields.
1867  Diamonds are discovered at Two Mile Flat on the Cudgegong River, near Mudgee.
Diamonds are discovered at Bingara.
1868  Diamond mining begins at the Reedy Creek-Cudgegong River junction, continuing to 1870.
1869  Sapphires are discovered near Gulgong.
1872-1873  There is a diamond "rush" to the Bingara area, with mining continuing until 1904 and 1909.
1872-1875  The discovery of diamonds in the Copeton area triggers another "rush". Mining continues until about 1922.
1876  Diamonds are discovered at the mouth of the Muckerawa Creek.
1877  Mining for precious opal in igneous rocks begins at Rocky Bridge Creek, a tributary of the Abercrombie River, in the Central West. Precious opal has the characteristic "play of colours". It has been found in volcanic rock, filling cavities in basalt, but this type of opal tends to be less valuable than that found in sedimentary rocks.
1880  Topaz is reported in the Glen Innes area.
1881  Opal is discovered at Milparinka, near Tibooburra in the Far West. Precious opal in sedimentary rocks forms when silica gathers in veins, fractures and other voids - and sometimes as replacement of organic materials (wood, shells, even bones).
1883  Diamond mining from deep leads begins at Copeton, continuing until 1922.
1884  Diamonds are reported in the Mittagong area.
Opal is discovered in sedimentary rock at White Cliffs in the Far West.
1889  Precious opal is discovered at White Cliffs.
1880s or 1891  Opal is discovered in sedimentary rock at Lightning Ridge (Wallangulla) and other localities in the area, but its commercial value is not recognised.
1890  Precious opal mining begins at White Cliffs (continuing to 1915 then going into decline).
Small-scale diamond mining begins near Narrabri (with some production to 1902).
1890-1891  Sapphires are discovered in the Wingecarribee River (with topaz etc).
1894  Non-alluvial or "hard roc" emerald is discovered at Emmaville and mined intermittently to 1908-1909.
1896  Opal is discovered at Purnanga and Grenville-Bunker Field. These occurrences are near White Cliffs and so extend the size of that opal-bearing district.
1897  Opal is discovered in igneous rock at Tooraweenah, near Coonabarabran.
A few diamonds are discovered at Mount McDonald (Abercrombie River).
1901  Opal is discovered in igneous rock at Tintenbar, on the Far North Coast.
1901-1905  Opal mining begins at Lightning Ridge - a good example of how small-scale mining operations can support a remote population centre - in this case a centre which produces some of the most famous (and valuable) opal in the world: the black opal. The first shaft was put down around 1901 or 1902 by Jack Murray, a boundary rider who lived on a property nearby. Some time later, possibly a few months, a miner from Bathurst named Charlie Nettleton arrived and commenced shaft sinking. It was he who in 1903 sold the first parcel of gems from the field for $30, not a fiftieth of the price that could have been obtained five years later.
1908  Opal mining begins at the Grawin-Sheepyard Field in the Lightning Ridge area, increasing the importance of the opal fields in the district.
1916  Diamond mining begins again near the Reedy Creek-Cudgegong River junction.
1919  Sapphire mining begins at Sapphire.
Opal mining begins at Tintenbar, continuing to 1922.
Sapphire mining begins near Inverell and Glen Innes and Tingha continuing, in the first instance, to about 1929.
1920  The Newfield opal area is discovered.
1930s  Gold and diamond deposits are worked at Airly Mountain, near Lithgow, during the Depression - with irregular operations to 1963 and again to the
1950  Dredging for diamonds (during gold operations) occurs along the Macquarie River near Wellington (until 1958).
1960  Spectacular growth in sapphire mining begins around Inverell and Glen Innes, continuing to 1980.
1985  Seminal work by the Geological Survey of New South Wales leads to better, more scientifically controlled exploration for opals.
1989  The Coocoran opal area is discovered in the Lightning Ridge district.
1994-1995  Minor sapphire production occurs in the Oberon district.
1995  The value of New South Wales annual sapphire production peaks at $11.4 million. New South Wales is a major world producer of sapphires.
1995-1996  The value of New South Wales opal production reaches an annual level of about $70 million. New South Wales (and Australia) is a leading world producer of opals.
1998-1999  The estimated value of opal production in the State is about $44 million.