There are a couple of jewels in the game that are transferrable (the Morganthe gems dropped by Baba Yaga), however there should be a couple of other jewels that are transferrable as well. These can be removed (not destroyed) and moved.
For pet jewels - there is one that I can think of: The accelerated Learner Opal. Basically this gives your pet one free training point after any battle in which it is used, and has a 5 minute cooldown period. Granted it is not much, but this should be a removeable jewel since it would be useful to move it among different pets that you would use under different battle conditions. Its a rare enough jewel to get, and it is not so overpowered that it could not be reusable among more than one pet.
Feel free to post other reusable jewel suggestions.
