Crystals or Mineral Inclusions:
Diamonds regularly have miniscule crystals or minerals imbedded within them and these can even be other tiny diamonds. Otherwise, any included and undigested gemstones are more often than not fragments of garnet, diopside, spinel, calcite, olivine, silica or iron oxide. Although the majority of these cannot be viewed prior to magnification, a significantly sized cluster or mass of crystals does detract from a diamond's appearance, lowering its clarity grade and value.