The iPhone 6s in Space Gray or often referred to as 土豪金 which translates to Earthy Gold or more commonly known as Rose Gold in some regions, but specifically 土豪金 refers to the rose gold or champagne color of the iPhone 6s.

However, if you're referring to the standard gold color, that would be Gold.

Here are the colors the iPhone 6s was available in:

Space Gray (深空灰)
Gold (金色)
Rose Gold (玫瑰金 or 土豪金)
Silver (银色)

Let me know if you have any other questions!