How do I boil down a gravy?
There are two ways to thicken gravy:


simmer down
Requires time, patience and a wide pot to get a large surface area for optimum evaporation. Simmering down results in very concentrated flavours (including salt, so be careful with salting in the beginning).
use a thickener
This is often something starchy like flour or corn / potato starch that binds the liquid. Note that the flavours won't be as concentrated, sometimes even a bit dulled by the starch.


So try your sauce and depending on the flavour level you have reached now, you should simmer longer, use starch or do both sequentially.

(If your guests are hungrily gnawing at the tablecloth already, whip out the starch, adjust the seasoning and serve asap ^_^)