document: A total of 2,488 medals, each weighing 500g, have been produced - with 812 gold, 812 silver and 864 bronze.
  They were made with "sustainability at their heart", say organisers.
  The gold medals are free from mercury, the silver and bronze medals are made from 30% recycled materials, and half of the plastic in their ribbons is from recycled plastic bottles.
  The designs feature laurel leaves - a symbol of victory in ancient Greece - surrounding the Rio 2016 logo, and organisers say they celebrate "the relationship between the strengths of Olympic heroes and the forces of nature".
  In line with the ecological theme of the Games, the podiums on which the athletes will receive the medals are made from organic materials and have been designed to be reused as furniture after the Games.
  There are 2,642 Paralympic medals: 877 gold, 876 silver and 889 bronze and each has a device inside that uses tiny steel balls to make a sound when they are shaken, allowing visually impaired athletes to identify the colour by increasing in volume from bronze to gold.
  The bronze medals have 16 steel balls and make the lowest sound, the silver medals have 20 balls and the golds have 28, producing the loudest noise.
  All of the medals also have the words 'Rio 2016 Paralympic Games' written on them in Braille.
summary: Rio 2016 organisers have revealed the medals that will be competed for at this summer's Olympics.