I bought several sets and used them at home, and also gave some as gifts for return favors, but some remained unused. They had been kept in their bags for a long time, and when I opened them, there were spots on the white inside of the box. However, I also saw them on the ones I use at home, so I'm not sure if they were there from the beginning or if they developed over time, but the chopstick rests were clean. My own chopstick rests are still in use. Sakura Horikiri.