Great question! Gold is a very poor choice of materials for cuffs; it's soft, not very strong, and extremely expensive. Since cuffs made of gold would be easy to break, they would not only be ineffective restraints but would likely be stolen by escapees as well.
Most companies opt for the more conventional steel cuffs, typically one of the harder stainless alloys for resistance to corrosion and tool damage. However, some still swear by simple leg irons of a design little-changed for centuries. A few have experimented with "free range" employees, bound to their workstations only by personal debt and vesting schedules, but this approach has proven much less effective.