Jewellery can be made from almost any metal or even material but certainly gold and silver is among the most popular choices for jewellery.
This is largely due to durability, malleability and cost.
Silver and gold are reasonably affordable (compared to platinum). They are relatively malleable and as such can be made into complex designs and set around stones.
In terms of durability, gold and silver are resistant to most environmental factors and despite some tarnishing can be worn on the skin without much change.
One important factor is the beauty of these metals in their own right, they both have a beautiful lustre making them the perfect choice for jewellery.