If it's not glass then don't panic, some newer designs use other materials;
Do all raybans have rb etching. If the etching is missing, or a low quality or painted on the glasses will be fake. If you order ray ban glasses they should always come with a branded leather case and cleaning cloth. In some glasses, the hinges are attached with philip screws to tighten these.
If the etching is missing, or a low quality or painted on the glasses will be. On fakes the etching will either be missing or of poor quality. If the etching is missing, or a low quality or painted on the glasses will be fake.