If you electroplate gold directly on silver, the durability will be limited. This is because silver atoms can migrate (diffuse) through the gold layer and thereby oxidize when they come in contact with oxygen from the air. However, it is a very slow process.
To prevent this, nickel was used as a diffusion barrier. However, it turned out to be able to cause skin allergies. Nickel is currently banned in jewelry and A.Brask does not use nickel.
With ALPHA GOLD® we have solved the diffusion problem by using another diffusion barrier as well as a protective layer for our gold-plated jewelery.