how can i repair a cracked lampshade?

i have a small round lampshade, made from a coconut shell. it has a pattern carved out of it so that the light shines through. it was dropped and now has a crack going round the middle. i would like to try to glue it together but am afraid any surplus glue might mark the coconut shell. i wondered if putting masking tape either side of the crack would be enough to stop the glue oozing on to the shell. should i try to glue this from inside the shell? could the glue be removed if it oozed on to the shell - if so what with? any help would be much appreciated. thanks