The precious metal gold is soft, heavy and of intensive yellow colour. Pure gold is 24 C (carat), however, because of its weight and softness, jewellery is seldom made of pure gold and no stones are set into such gold. Coins are made of 24C and 21C-22C because this is a simple form of investments and savings. Jewellery is made of 8C, 10C, 14C, 18C, 21C-22C gold. Jewellery made of 21C-22C gold is predominantly worn in Asia and America, and this jewellery is of intensive yellow colour and rather heavy. The sign or stamp for 18C gold is 750. This gold is characterised by firmness and is of moderate yellow colour. It contains 75% of gold and 25% of other metals, such as copper, silver and other metals. The 18C gold is used for making the designer and expensive jewellery. The sign or stamp for 14C gold is 585. It is of light yellow colour and contains 58% of gold and 42% of other metals. It is extremely solid. This type of gold is mainly used for mass production and commercial use and is lighter than 18C gold. The sign or stamp for 8C gold is 333, and it only contains 33% of gold and 67% of other metals. Therefore, this jewellery is not considered to be gold jewellery in many countries, because it is very light and of light yellow colour. Gold is metal, natural ore of solely yellow colour. However, jewellery is also made of white and red gold. These colours are obtained by adding certain metals into the gold. In order to obtain white and red colours, rhodium and copper are added respectively. There is also black rhodium, which helps the jewellery get an antique appearance. Eventually, white gold is plated with white rhodium to become entirely white. Platinum is extremely solid and heavy metal of white colour. The platinum jewellery is very simple and decent, and is therefore often combined with diamonds. Prices of all metals vary at the world exchange market daily. Silver and copper are rather cheap, while gold, silver and platinum are more expensive.