As with all jewelry, if you don't care for and maintain your pearls, you risk the chance of discoloration and yellowing. Avoid contact with perfume and chemicals in general. Also skin chemistry, which can change depending upon the weather, can be a factor if your skin is prone to acidity. Acidity will cause the pearl to lose its luster over time. Perspiration, humidity, suntan lotion and hair spray all affect your jewelry so be sure to keep your freshwater pearls clean. And remember to apply your makeup before putting on your necklace.