Is it a very fine crack or does it show a gap? Can you take the grip off without losing any pieces? Also, is there metal directly behing the pear itself?
If you can carefully remove the pearl grip and it is a fine crack, wax or place a small piece of celophane on the frame. This will keep you from gluing the grip to the frame. Replace the grip and lay a fine bead of super glue on the crack. If it is a bigger crack, you can often find gap filling super glue. Use the glue sparingly.
Once sealed, lightly sand the area with 600 wet/dry paper then go on with polishing compounds. When I did this on guitars I used Meguiars Mirror Glaze. You can usually find it at auto supply stores.
Here's a place with lots of super glue options.
Take it slow and easy. Good luck, let us know how it goes.