The difference in the amount of gold alloy can attribute to various factors. Firstly, the purity level of the gold used in the alloy can affect the amount required. For instance, if a jewelry studio is making jewellery that requires more durability, they may incorporate more alloy metals to increase the strength of the gold. Thus, the amount of gold alloy varies based on various factors. They include the gold purity, desired properties, and availability and cost of the necessary alloys.