The exact thing I want to know how to say is 'The wristwatch is made out of gold' and 'The wristwatch is gold and black in colour'. Would saying this be the same as talking about a house being made of wood (for example)?
While in English the word "gold" can easily mean both the colour and the metal, the Japanese word for "golden colour" is "金色" and the word for gold (metal) is "金" (read as きん), which makes it less ambiguous.
Although there is also word "黄金" which indeed can mean both the colour and the metal, and "金" read as "かね", which can mean "money" or "metal" in general (any metal, not specifically gold).
"made of ~" could be translated as ~で作った or ~から作った (or できた).
So I would translate those as:
The wristwatch is made out of gold: (この)腕時計は金から作った。
The wristwatch is gold and black in colour: (この)腕時計は金色と黒だ。
黒と金色の腕時計 - "black and golden coloured watch"
金の腕時計 - "gold watch"