The purity of the gold is stated as ‘percentage’ in chemistry, and it is stated as ‘carat’ in jewellry. According to this, 24-carat gold represents 100% pure gold, and 22-carat gold represents 91,6% pure gold. The 22-carat gold is integrated with 8,4% of other metals. The colour of the gold turns into greenish when silver is added. If nickel and platinum are added, the colour turns into white; if zinc is added, the colour of the gold turns into yellow; and if copper is added, the colour turns into a colour that ranges between yellow and red depending on the amount of the copper. It is impossible to find 100% pure gold, but 999,9% pure gold. Eighteen-carat gold contains 75% gold; and fourteen-carat gold contains 54,5% gold. If the supplementary metal is silver, the gold becomes yellow gold, known as green gold in jewellery.