Look at the surface of the crystal goblet. Notice the pattern on the surface of the glass. Certain patterns will contain flowers, vines or other designs. Each of these patterns has a different name by which it is identified. The design can be compared with a list of common designs available online.
Confirm that the crystal goblet is actually etched and not decorated by another method. Feel the surface of the glass with your fingers. Etched glass will have a textured feeling along the lines of the design. Glass that is not etched will be smooth. If the glass is smooth, the method of creating the design could be by imitation etching, created with etching craft fluids or paint.
Look at the bottom of the goblet for a label. Real etched glass will have been created by a professional company known for glass etching. If there is no label or the name is not associated with genuine etching, the crystal goblet's etching could be fake.