Why cant we manufactue gold?, after all we should know the make up of the stuff and how its created and we can make diamonds so why not gold, silver or platinum.
or am i just being stupid?
It is never easy to make a new element since every element has a unique number of protons in its nucleus. Nuclear fusion, nuclear fission and neutron bombardment followed by nuclear decay can make new elements but it's not feasible for Gold.
All matter was created within stars as a result of nuclear fusion, Hydrogento Helium etc and so on down the peiodic table. when the star goes nova, some of this matter is thrown out into space and then goes on to form planets etc. It is said every atom in your body originated within a star. Needless to say its very difficult and cost prohibative to try and duplicate this on Earth.
Easy, all you need is a giant fusion reactor about 100 times the size of the sun, wait about 5 billion years for it to go from hydrogen to helium to carbon to iron to silicon etc etc ...... through the rest of the periodic table and viola! sorted. As Hyperion points out it takes nuclear fusion, ie stars, to make heavy elements and the really heavy ones need really big stars the sort that would supernova. Mankind hasn't really got the fusion thing going yet.