Since it seems crystals in general are a lucrative harvest for perhaps RMT and botters, why not make it like it is in FFXI? Everything has an elemental affinity. Mobs can drop crystals, elementals can drop clusters. Crystals can be broken down into shards, clusters into crystals. I can't see why this can't be done. It makes no sense to be unable to break down clusters and crystals as it is.