To ensure high quality direct gold restorations, which of the following conditions should be satisfied?
High-quality direct-gold restorations can be ensured only when four principal conditions are satisfied: 

The appropriate gold form is used for each specific clinical situation.
The material is used only where it is indicated.
A perfectly dry and clean field is provided.
The material is properly manipulated with the correct instruments. Obviously, these conditions can be satisfied only if the clinician has acquired the necessary knowledge, skills and experience.

Ref:Phillip’s Science of Dental Materials ed 12 pg 414
The appropriate gold form is used for each specific clinical situation
The material is used only where it is indicated
A perfectly dry and clean field is provided
All of the above