Pastel has a beauty all its own. It's permanent. It will not fade or degenerate. High quality pastel is near-100% pure pigment held together with a binder such as gum arabic. Then it's formed into sticks. Don't confuse pastel with chalk. It resembles chalk in shape; but that's where the similarity ends. Pastel is the most permanent of all the media. Painters from the 1800's - Toulouse-Lautrec, Mary Cassatt, Manet, Degas - used pastels to create amazing works of art and are intact today, as beautiful as when they were created.
The height of richness, sparkle, luster, vibrancy is unique to pastel. As is the case with most informed pastel artists, I never use spray fixative. Ever. It robs the art of those distinct and enchanting qualities.
Most important is the careful handling of the unframed pieces until delivered to the frame shop. Pastel, a dry pigment, can bruise and damage without proper care. A reputable framer who regularly works with pastel art will know how to handle it. It's absolutely paramount that there be an air space between the artwork and the glass. A space is created if a mat is used in the framing design; however, I prefer most pastel art without mats. There are several materials used to create the spacer. It might be a slim piece of balsa wood or acrylic that tucks under the lip of the frame between the artwork and glass. A good quality UV glass and acid free backing board contributes to the longevity of the artwork and will be enjoyed for generations.