Am I entitled to claim the jewelry I bought for my mother as compensation for what was stolen, and not include it in her inheritance?

If the jewelry was purchased for your mother as a gift and she took possession of it, then you do not have the right to claim it after her death; because it has become an inheritance to be divided among the heirs. However, if it was given to her as a loan for safekeeping, and this is legally proven, then you have the right to reclaim it. In any other case, you do not have the right to reclaim it unless the adult, mature heirs willingly relinquish their right to it.