A special place
Diamonds deserve its' own special place in your jewelry box, away from other rings and necklaces that could potentially scratch it. The best place to store it would be in a soft jewelry pouch - Many people do not know that the humidity in the air can also be bad for diamonds that are stored for a long time. Never leave the diamond on a sink, you could forget about and it gets lost or it could fall down the drain.
Take the time to inspect your diamond, especially the setting that it is in, although it is not likely, it could come loose after years of wearing it. A professional jeweler would be able to fix the problem immediately; they could also clean your diamond. As rule you should take your diamond for inspection and a clean once a year. Rather be safe than sorry when it comes to diamonds, it is not something you easily replace.
Avoid using creams, oils and body spray etc. with your diamond on, overtime it can lose its sparkle. Rather take your diamond off when doing house work and it can also easily chip. If you do want to clean your diamond at home then you can leave it to soak in warm water with a touch of ammonia (stay away from other chemicals like chlorine as it could loosen the diamond setting). Remember to gentle scrub using a soft bristled tooth brush and then to pat dry with a very soft cloth. It is actually better for the diamond to be cleaned regularly by yourself, as the oils from our natural skin will cause a build up anyway. Avoid wearing your diamonds during outdoor activities and when playing sport, it is in any case a special item that should be appreciated. Rather keep a small safe box in your bag if you know you are going to take part in outdoor events.