Maintenance of your gold necklace is always an important practice to know, especially when it comes to daily activities like taking a shower and sleeping.
The general rule when it comes to wearing gold necklaces in the shower is to try and avoid it as much as possible, especially on a regular basis. Wearing a gold necklace in the shower will not harm the metal itself, but it can reduce the shine of the necklace, making it appear dull, or tarnished.
Pure gold will not rust when in contact with water, however, many necklaces contain other metals too. These metals can react with the shower gels, perfumes and colognes, and other products typically used in the shower, and end up ruined.
Sleeping with your gold necklace on is generally not recommended if you want to keep your necklace intact for as long as possible. Although gold necklaces are usually strong, when you sleep in your necklace, you do risk breaking it. When you move in your sleep, the chain links wear against each other, increasing the chance of them becoming weaker.