Whenever I get a new cork-handled rod I always immediately seal the cork with U-40 Cork Seal. Over time, cork can get broken down from all the sweat and dirt from your hands, and it ends up looking pretty bad. The U-40 Cork seal is available from Netcraft and is only $5.00 and really easy to use.
I just apply a ton of it with a big horse hair brush until the cork starts to soak it up. When it will not soak any more up I wipe off some of the excess with a rag and hit it with a hair dryer. This will dry it in less than a minute. Order some now so next time you buy a new rod it will be there ready for you. I say this only because it works the best when applied to new cork. If you don't have it around when you bring your new rods home they will end up in use before being sealed.
After drying the natural color comes back.