How to bend the quartz bar with 1 mm diameter and 300 mm length?
One very easy test is for thermal conductivity. Take an ordinary drinking glass or an empty Coke bottle and stand it in a shady place along with your bracelet for about twenty minutes so that they both reach room temperature. Then in turn touch each item with the tip of your tongue. If your bracelet feels colder than the glass it is quartz, if they feel the same you have a glass fake.
It is certain that quartz will scratch glass, whereas glass will not scratch itself!
Quartz can be broken too, so that's not a good test. A good specimen of quartz is colorless and flawless; visual comparison with glass would not really help. A hardness test could tell you something: if the necklace pieces can scratch glass but not quartz, then they are glass. If they can scratch quartz, then they are quartz. The refractive index of quartz is different from most glass. Some jewelers can test refractive index for you.
Try to break it. If it breaks, then it's glass (a.k.a worthless). If its quartz, it won't break and you're good
