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To cope with the existence for diamonds,mines have been dug extensively in South Africa,SouthAmerica,and Russia.From the mines,the most precious stones are sent to factories where they are____.It is a false impression that polished diamonds are obtained directly from the stones. It is true that the stones are dug____from them but workers need to use machines to cut them into the sparkling and well-formed diamonds which see in jewellery shops.The value of a diamond depends on its weight and on how perfect the shape is.