Jean,
I do a lot of cooking at home, I love cooking when I make rabbit stew or beef stew and I need to make my own colouring I burn some sugar on a spoon or in a pan. Then when it turns black I extinguish it with water giving me a very dark colouring. You can make your gravy dark in this way too. Here in Belgium you can buy ‘Buismans’, which is ground burnt sugar, the Dutch use it a lot mixed in with ground coffee to make it stronger without using too much coffee. You only need a very small amount, too much is very bitter.
PS, DON'T burn sugar in a confined area as the fumes will knock you out cold! If you have an extractor turn it on full.