These gold alloys are added to 24k gold to produce karats and colors. Supplied in grain from and mad efrom highly pure metals, they are complete gold alloys because the only thing you add is gold itself. It is important that only prue (.999 fine) gold is used, since any contamination could affect the color and ductility. Gold alloys blends easily with gold with optimum hardness and annealing properties, leading to production of defect free jewelry. gold allys and gold should be mixed and grained prior to use in casting.