I recently had a rose gold project that I was really excited about doing, but I was also concerned because I know rose gold can be quite finicky and it tends to change into an ugly color when oxidized. So I branched out and bought a small bottle of Firescoff, since it claimed to protect the color of metals.
After I tried it, I realized it did! My rose gold didn't even need pickling!
What it is: a ceramic flux spray, that replaces flux, firecoat and pickle. It cleans up with just warm water.
To use Firescoff, you just need to heat your piece up slightly (the directions say to around 250 degrees F.) A tip I learned was that you can put a drop of water on your piece and heat it until the water boils off. This means you have the right temperature.
Next, spray a even mist over the entire piece. When you put the fire back on it you will see it bubble up into a white powdery coating. If you can still see the sheen on parts of your metal, you may want to spray again.
As soon as your soldering is finished, you can just clean the rest of the white coating off with water. Voila! No need to pickle, and the rose gold color is still the same as when I started.
Firescoff isn't super cheap for the size that you get, though. So, stick to your regular method for silver and other metals that do fine in a pickle. But for certain projects, it's good to have on hand!