This will be the stud that you never take out and you never have to worry about tarnishing or getting infected. Gold-filled jewelry is the closest thing to solid gold. Gold-filled pieces contain more than 100x more gold than gold-plated jewelry. For an item to be classified as gold-filled, 5% of the total weight of the item must be made up of gold. The layer of gold is much thicker and stronger, therefore more resistant to tarnishing. If you're looking to invest in a lifetime piece, this is for you!