First of all, I want to remind you that it is impossible to determine the authenticity of a gold necklace simply by observing its appearance and feel. The color and impression of fire can be used as the basis for judgment, but it requires professional knowledge and experience. If your gold necklace is pure gold, it should have the following characteristics:

1. Thousands of pure gold is a kind of metal with very high gold content. Generally speaking, the higher the purity, the purer the color, so if your necklace looks impure, it may be fake.

2. After burning on the fire, the color of thousands of gold will not change, and it still appears yellow. If there is color change or impurity, it may be a fake.

3. Real thousands of gold jewelry usually has a clear manufacturer's logo and number, which can be used as a basis for judgment.

If you find that colorful light can be reflected in the middle of the pendant, it may be due to a new technology. This process is similar to the diamond cutting surface, which can reflect colorful colors. But this is not the only basis for determining authenticity, because imitations may also adopt similar processes.

If you still have doubts about the authenticity of your gold necklace, the best way is to find a professional jewelry appraisal agency for appraisal. They will have special equipment and methods to detect and evaluate metals, thus giving accurate results.