It is best to use ammonia to clean diamond jewellery. All you have to do is dilute one volume of ammonia with three volumes of water and allow your diamond ornament to rest in it for thirty minutes.
Ultrasonic cleansers are the best tools to clear dirt from diamond ornaments. The device sends low-frequency sound waves along with a vibrating solution to remove the dirt.
Take professional help if you want your diamond ornaments to be cleaned in the safest method.