14K and 18K Gold
Everything deserves some loving, even something as strong as Gold. To maintain its beauty, scrub lightly with a toothbrush and warm water.
Diamonds
Even diamonds have their weakness. They may be the hardest natural substance but can still suffer from chips & small fractures from sharp blows! Use warm soapy liquid and a toothbrush, rinsing the stone and setting afterwards to ensure there is no residue. Remember to dry the jewelry well !
Gemstones
Gemstones are not fans of water or chemicals. Also, prolonged exposure to sunlight may cause certain gemstones to become paler. So a jewelry cleaner both online would work best for gemstones and honestly any jewelry.