The phenomenon of crystal twinning via mutual contact was identified during the experimental modelling of diamond crystallization. The twinning probability amounted up to about 50%; thus surpassing that (2%) due to contact with the walls of the crystallization chamber.

Formation on Growth Twins, on Mutual Contact of Diamond Crystals. A.I.Chepurov, V.M.Sonin, A.I.Fedorov: Crystal Research and Technology, 2000, 35[8], 921-6