18k gold necklace button, is there any rubber pie in it?

Usually not.

The most common clasp of 18K gold necklace is spring clasp, which is the longest clasp on the market at present. In spring buckles, very slight and fine linear metal is usually added. Used to increase hardness and hardness.

It controls the opening and closing of the buckle through a mechanism equipped with a "spring", which is very convenient to wear and does not need to be forcibly broken like a W-shaped buckle. Mostly used for high hardness K gold. The advantage is easy to wear, but the disadvantage is limited life.

There are several kinds of buckles with the same "mechanism" as spring buckles, such as lobster buckles and square buckles. Generally, big-name jewelry has many hidden buttons, which are locked into the groove by spring pieces and fixed. Because we want to highlight the overall effect of jewelry, the hidden buttons are either one of the decorations of the necklace, designed exquisitely, or directly made into invisible shapes.

18K gold lobster clasp

Because it looks more like a lobster, it is called a lobster clasp, which is more suitable for men's bracelets inlaid with 18K gold. Of course, there are many other lobster buckles made of precious metals, which are very convenient to adjust the size of the bracelet. Because the appearance is not beautiful enough, its use is limited, and it is only common in cheap jewelry. If it is not made of K-gold, it will be easily damaged and difficult to repair.