Curtain crystal” doesn’t seem to refer to a specific term or object in common usage. It’s possible you may be referring to a crystal or glass ornament or decoration used in curtain arrangements or window treatments. These decorative crystals are often added to curtain tiebacks, curtain rods, or curtain valances to enhance the overall aesthetic of a room. They can come in various shapes, sizes, and colors, adding a touch of elegance and sparkle to window decor. If you have a specific context or use case in mind for “curtain crystal,” please provide more details, and I’ll be happy to assist you further.