Fine, thin chains are the default chain that come on most pendants, charms and necklaces. These chains are frail, delicate, thin and extremely fragile. Any slight yank could break them apart or pull the links open.
Why do necklaces break so easily?
It is part of normal wear for a clasp on a necklace or bracelet to loosen, hinges to wear or prong tips to break. It is also normal to need clasps to be routinely checked and tightened. Wearing jewelry 24 hours a day exasperates this wear.
How do I keep my necklace from breaking?
Don't pull a chain over your head to put it on or take it off. Remove necklaces when holding or playing with a child. Do not wear jewelry chains when participating in sports or other activities where the chain can get snagged. Don't wear jewelry to bed.