ANy color wood stain works. Then rub in several coats of oil stock finish. I like Birchwood Casey's Tru-oil, and that is what I have on hand. I have also used Linspeed. Then there is tung oil, varnishes, shellac, and even polyurethanes finishes. They will all work but may give you a different finish than you want. Test them out and use the one you like. You want to seal the pores of the wood so they don't collect and hold crud, or metal. You don't want to hold silicates because they are very hard, and will act like emery cloth, slowly wearing down the sides of your muzzle over time. Try to get a muzzle protector for the rod and use it always to center the rod in the barrel, and protect that all important muzzle crown.
I use a full length steel rod with a nylon bore protector for my range rod, and experimental loading rod. When I settle on a load, I mark the wooden hickory ramrod that goes under the barrel of the gun and out in the woods for the load I am using. I have used a knife edge, and just pencil to make my witness mark on my hickory stick. If I have to pull a ball, using that steel rod makes the job a lot easier. The muzzle protector centers the rod so I can run the jag into the center of the ball, and the steel rod give good purchase for me to grip and pull on. It cleans off easily after use with the wipe of a rag, and it is too hard to hold and silicate debris. I wouldn't be without one at the range. With my hickory rods, they get wiped down after each loading so they stay clean, and don't gather crud. With that close attention, I don't have to worry about them wearing the muzzles of my guns.