COMPLEX MULTIPLE TWINNING OF CRYSTALS AS A CAUSE OF ANOMALIES IN THE DEVELOPMENT OF UNIQUELY SHAPED DIAMONDS FROM THE ALROSA COLLECTION

Multiple twinning of diamond crystals, combining polysynthetic and cyclic types of coalescence in accordance with the spinel law, leads to the appearance of rare forms of diamond, unusual in appearance and difficult for mineralogical analysis. Their interpretation is especially complicated by the significant dissolution of the crystal's faceting elements, which erases the usual morphological signs of the boundaries of twinning growth between the components of regular accretions. Observing the symmetry of the relief pattern of dissolution provides some assistance in establishing them. The article discusses examples of diamonds from the collection of rare forms of the ALROSA company associated with the origin of the twinning process.