Since this word is made up of a single kanji you would normally think it uses the kun'yomi reading. Not this word, though. It still uses the on'yomi reading, which you learned with the kanji. Don't confuse this one with お金, though. That one uses kun'yomi which you know because it has a hiragana attached.
I gave her a gold necklace.
If I had money, I would like to buy the gold Rolex that Kim Jong-un has.
This yarn will turn into gold in 24 hours and I’ll give you some as a Christmas present, so you should appreciate me more.