A non-abrasive polish such as Flitz can often remove light oxidation without damaging a knife. Note that some finishes may be slightly marred by even a non-abrasive polish and the etch on Damascus may be lightened by using polishes. If oxidation develops on a satin finished knife, it is often possible to remove it by rubbing a 3M pad in the direction of the original finish lines. Inlays often include delicate materials such as sperm whale tooth, or giraffe bone. All of these, as well as other natural handle materials such as exotic woods and antler can dry out if not treated correctly.
All natural materials can dry out and become dull looking, shrink, or crack in arid climates.
If you live in an area with low humidity, store knives with natural materials in a case with a small glass of water. It is also important to protect your knife from high heat as well as cold. Don't keep your knives over an operating fireplace, which is very hot and dry. Equally so, don't store in a cold garage or workroom. Repeated exposure to your skin oils will allow ivory to acquire a patina faster, and an occasional wipe with Kurobara Camellia Oil will add luster to any handle material.