The potential possibility of intergrowth of two bulk crystals to single crystal was demonstrated on the example of beryl, Be3Al2Si6O18, growing under hydrothermal conditions. The result has practical importance because it allows increase of the yield of useful product on a single growth cycle. The fine structure and composition of the area adjacent to the splicing boundary was investigated. It was demonstrated that the influence of the intergrowth border of two crystals spliced in parallel is entirely analogous to the affect of a twin boundary. This analogy extends as well on the specific morphology of the growth front generated by the boundary as on the growth velocity of the surfaces adjacent to the boundary that is increasing 3-10 times. In addition we show that the spliced crystals tend to align near single crystal orientation. The assumption on the nature of the driving forces of such impact was made. We also suggest assumptions about the nature of these orientational forces.