■ Tanzanite and Tsavorite are closely related. Their chemical compositions differ only by the presence of chemical OH groups in Tanzanite.
■ First, under high pressure and temperature in the rising magma, Tsavorite garnets form. Later, if certain fluids are present when the temperature and pressure drops, Tsavorites can recrystallize into Tanzanites. Some crystals have even been found with a core of Tsavorite and an outer layer of Tanzanite!
■ These two gems are found in the same areas and mines and are connected in gem traders' minds - since we source them from the same miners and rough dealers in the same places.
■ Large faceted Tsavorites are far rarer than Tanzanites due to the higher pressure (& higher internal stress) when initially forming.
Isn't it amazingly cool?