To plate each of the mirrors on the James Webb Space Telescope (the successor to the Hubble), engineers at Quantum Coating Incorporated use less than three grams of gold. They use a vacuum coating chamber to create the sheen, which is important in reflecting specific kinds of light, in this case, infared light.
These hexagons make up the primary mirror, which will be about 6.5 meters wide. This is about 2.7 times larger than the diameter of Hubble, or about 6 times larger in area.
The Webb telescope is set to launch into space in October of 2018, and scientists are working hard on assembling the mirrors and other instruments that will be sent into space. It will go about a million miles away and peer into the deepest reaches of space, where it should be able to see back in time 13.4 billion years, into the beginning of the universe (which is about 13.7 billion years old).