DIAMOND CARE To keep your diamonds sparkling, it's important to clean them. Recommended methods: Professional Cleaning Free, professional cleaning and setting-integrity checkups are included with every diamond purchase, for as long as you own your diamond. Mild Liquid Detergent Soak in a small bowl of warm, sudsy water made with any mild liquid detergent. Gently brush the diamond jewelry with a soft toothbrush. Cover the drain, then rinse under warm running water. Pat dry with a soft, lint-free cloth.