I will teach you three simple methods how to get an amber color stock.

1. You should add 1-2 small onions in their skins cut in half and fried on the frying pan without oil until it gets brown.
2. Fry carrots in butter until the butter gets yellow and add the cooked carrots to the stock.
3. Dilute pinch of curcuma powder in half a glass of warm stock and mix it in the stock at the end.