Pure (fine) gold is 24 ct in weight. There are also 22ct, 18ct 14ct and 9ct golds. 22ct is mostly seen in India, Asia and the Middle East and is very yellow in colour.
14ct Rose Gold was common in antique jewellery that was made over 100 years ago.
White Gold is created by adding Nickel, Copper and Zinc. The amounts of these metals creates the white colour of the gold. Rose Gold has more Copper and less Silver than Yellow Gold to enhance the pink colour but also has Zinc.