My boyfriend sent an amber necklace with an appraisal certificate, but I don't know if it's true or false.

It's true. As long as it is a professional and formal appraisal institution, it uses the name of the national standard. The name on the appraisal certificate can only be written in amber. Natural amber has a light texture. When you put it in a place without any inlays, when you put it in water, it will sink to the bottom. But you don't have to worry. You add dissolved brine to it. When the concentration of salt is greater than 1 ratio 4, 1 part salt and 4 parts water, real amber will float slowly, while fake amber will not.