18                             PRECIOUS STOXES doubt—for as we have seen, no human means have as yet been forthcoming by which the crystals can be changed in form, only in arrangement, for a diamond crystal is a diamond crystal, be it in a large mass, like the brightest and largest gem so far discovered—the great Cullinan diamond—or the tiniest grain of microscopic diamond-dust, and so on with all precious stones. So that in future references, to avoid repetition, these groups will be referred to as group 1, 2, and so on, sis detailed here.