With the high end Furutech connectors every detail is really well thought out. The plating is the best I've seen anywhere, it is a near flawless mirror finish, and this is true even for their lower end products. Conductor material is their alpha copper for most high end products, and afaik the GTX is the only receptacle to use pure copper as it is too soft to maintain the springiness required, so Furutech added a stainless steel spring to the pure copper contacts. A lot of attention is given to vibration control as well, the stainless/carbon fiber used in the CF series connectors was chosen for it's damping properties. They even add damping material to the plastic used in most of their connectors including the GTX. The AC plugs also have grounding straps for the screws so any metal parts used in the plugs is grounded. The wire clamps are curved for better contact in their plugs, receptacles and IECs as well.
As for the wire, it'll probably be a 10g twisted pair with the ground run separate or counter-rotating around the L/N twisted pair, and with this cable assembly inside a conduit.