It is recommended to clean your chandelier every 12-24 months to ensure it is looking it's best and sparkling like new. Although this sound daunting and hard, it really isn't much different to cleaning a table or piece of furniture once you get the hang of it. 
First and the foremost is that the light is switched off (keep the power off until completely dry).The next step is to get a bucket and fill around 20% full with hot water, then add approximately 5% white vinegar.
Now your ready to dip your micro fiber cloth (available from most supermarkets and all hardware stores) in the mixture. Squeeze your cloth so it is damp, but not dripping and wipe carefully over the crystals. Adding the white vinegar to the mixture means the water completely evaporates and leaves the crystals pristine without streaks. 
There are also spays you can buy on the market, however we find that vinegar, warm water & a little elbow grease every 12-24 months will provide a much more effective clean without affecting your electrical and metal components over time.
If would prefer to have your chandelier cleaned for you, there are chandelier cleaning business in most capital cities of New Zealand.