There may be a brown diamond with a shade or colour named gold. But always, gold is gold: a metal; diamond is diamond, an alltrope of carbon.
You 'get' them from mining for them in the earth. You can also purchase them in any jewelery store in the world.
They are used for jewerly and sometimes sold for money.
There are many different qualities of both gold and diamonds. There is cheap gold (the lower the karat as in 14K, 18K, 24K gold, the less valuable it is. Same holds true for diamonds. There are...
Diamond is the strongest material know to man.