The oldest gold artefacts date from around 5,000 BC. The radiant material attracted people’s attention even in those times and became a coveted substance. Gold is rare, prestigious, corrosion-resistant, malleable and seemingly timeless. For watches and jewellery, however, this precious metal is too soft in its pure form.
The material’s strength can be increased by adding various alloy components. When producing yellow gold, the goal is to strengthen the material while maintaining the rich colour of the fine gold. Lange uses yellow gold with a purity of 18 carats (750 ppt) for cases and buckles. For some winding rotors, 21-carat gold is used, which is equivalent to 875 ppt purity.