This is a yellow gold alloy of fine gold with silver and copper, similar to fine gold.
The ratio influences the colour. As the gold content decreases, the depth of the yellow tone also decreases very quickly. Usually the ratio of the metals added to the gold is about 1:1; the tones and colour intensity can be chosen continuously and arbitrarily. The colour ranges from light yellow with a clear silver content to yellow-orange with the reverse ratio to the copper added. Due to its high recognition value, yellow gold is by far the most popular gold colour worldwide.