In conclusion, we have shown that DCT can be used to identify phases with previously unknown crystal structures, even within bulky reaction vessels, and it can be used to characterize grain orientations. Combining the phase identification of large crystals with their growth mechanisms should lead to future studies that can engineer the growth conditions, such as changing the temperature profile, the starting stoichiometry, etc. in order to obtain the preferred phase and/or morphology. All tomographic analysis was performed without a synchrotron X-ray source and without opening the fused silica tube, showing the possibility of further study on sensitive samples and in-situ measurements during the growth process over a prolonged experimental period. Single-crystal UV-vis-NIR spectroscopy measurements confirmed rhombohedral KBiS 2 to be a semiconductor with an indirect band gap of 1.21 eV, which is corroborated by first-principles calculations. The parallels between the topological insulator candidate TlBiS 2 and isostructural KBiS 2 can be investigated in detail with subsequent optimization of crystal growth.