Please sanitize the nephrite jade egg before your first use.
After use, clean, dry, wrap it in a soft cloth, and then store it in the provided pouch.
You can sanitize it by boiling, brushing, washing it with soap then rinsing thoroughly with clean water.
Nephrite is harder than steel because it has a tightly packed interwoven fibrous structure that makes it very tough, strong and dense.
Nephrite jade is heavier than most stones. This makes it a perfect choice as yoni egg.
So, don't worry to damage your nephrite jade egg. It is very strong.
For fake jade eggs such as the one in the picture below that is made from serpentine, if boiling the stone egg, it may de-color. That is why some web sites warn "Not boil the stone egg as the stone might loose some of its properties". In other words, if a seller tells you do not boil the "jade egg", the "jade egg" is fake jade egg (jade simulant).
There are only 2 types of jades: nephrite and jadeite. Both are very strong and very dense. Boiling or brush cannot damage nephrite or jadeite.