How is sapphire mined

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Ruby is usually found in metamorphic rocks, such as those in the Harts Range in the Northern Territory. However, a more transparent, gemstone-quality ruby comes from a few areas in eastern Australia where it has been brought up from underlying metamorphic rocks by volcanic action. Marc Antoine Gaudin synthesised the first rubies by fusing alumina with chromium in Ten years later Jacques- Joseph Ebelmen made artificial sapphires by fusing alumina with boric acid.

Auguste Verneuil developed a process for producing large flawless sapphires and rubies in These crystals have many industrial uses including as mechanical bearings, as laser components, and in optics.

Sapphires and rubies have been found in all eastern Australian states, including Tasmania. The Kings Plains area, near Inverell, has some of the richest deposits of gem-quality sapphires ever mined. In addition, sapphires have been recovered from old tin workings along the Weld River in Tasmania. There are many sites where fossickers can try and find sapphires and rubies in these regions too.

The most significant occurrence of ruby is near Gloucester, near Mount Barrington, an old volcano. Rubies have also been found in the vicinity of the Macquarie and Cudgegong Rivers and near Tumbarumba. See map. Currently commercial mining of corundum including sapphire and ruby still occurs at the Anakie and Lava Plains placer deposits in Queensland, and the New England area of New South Wales.

Open pit mining is used to extract the corundum ore from the gravels. In many cases the mining operations are small and the pits quite shallow. Tools used might include jack hammers, excavators or shovels. Some countries in Africa and South America use high water pressure mining to produce large quantities of rough corundum gems.

However, many gem buyers boycott companies using this practice, because this method strips away all the top soil destroying the local environment. Once mined, corundum can be separated from clay and gravel because it is more dense and heavy.

Usually, the gravel is broken up and sorted into size fractions in a rotating drum trammel , and then washed either by hand or with a high pressure water jet, over filters with various size holes. The heavy grains will sink and the lighter materials, like clay, will wash over the top.

The remaining material also contains other heavy minerals such as magnetite and zircon. Magnets can be used to get rid of magnetic material and then zircons are removed by hand. The corundum is then visually assessed and graded according to size and colour. Sapphires and rubies can be artificially altered to improve their value or appearance.

Heat and irradiation can enhance the colour intensity as well as the clarity of the gemstones. Sometimes sapphires are heated in the presence of a material that can penetrate into the crystal and change the colour.

Gems can be coated with a light film for protection and surface fractures can be filled with oils, waxes, resins or glass. The cut and polish on a sapphire or ruby is determined depending on the colour and shape of the crystal. Sapphires and rubies can be cut in a number of different ways because the crystals are formed as a hexagonal shape. The majority of gems have Oval, Round and Cushion cuts. Rubies are generally cut with the top perpendicular to the vertical crystal axis.

This displays more of the purple-red colour rather than the orange-red colour. Regardless of the shape of the gem, the edges and the facets on the top of the sapphire or ruby the crown , are cut to be symmetrical.

Large sapphires that are not suitable for cutting can also be carved. Crystal structure of corundum. Sapphire and Ruby. White Sapphire Engagement Rings. Pink Sapphire Engagement Rings. Purple Sapphire Engagement Rings. Yellow Sapphire Engagement Rings. Green Sapphire Engagement Rings. Blue Green Sapphire Engagement Rings. Peach Sapphire Engagement Rings.

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