Can a tanzanite's origin be proven?
Yes, trivially, and it tells you nothing. Every tanzanite is from Merelani, so origin distinguishes no two stones. Traceability is the harder question.
READ
Gemmology, origin and colour — what tanzanite is, where it comes from, and how it is judged.
Is all tanzanite heat treated?
Effectively all of it, and it was probably brown in the ground. What the heating does, and why unheated is a premium worth declining.
READ
What is tanzanite? The stone, the source, the colour
Tanzanite is the violet-blue variety of zoisite, mined commercially in one place on Earth. Its colour is decided as much by the cutter as by the crystal.
READ
Tanzanite against sapphire and diamond
Tanzanite is geologically rarer than diamond and usually costs less. Both are true, and why they do not contradict each other is the useful part.
READThe other gem from Merelani: tanzanite and tsavorite
One hillside produced two new gemstones in 1967. Both are coloured by vanadium, and one of them is never treated.
READ
Why tanzanite is found in only one place on Earth
One deposit, about eight square miles, and a formation sequence that had to happen in a particular order. The geology is remarkable without the sales argument.
READWhat tanzanite is made of: the chemistry behind the colour
Ca2Al3(SiO4)3(OH), orthorhombic, coloured by trace vanadium. The formula explains the three colours, the cleavage plane and why heating works.
READ
December's four birthstones, honestly compared
Turquoise, blue zircon, blue topaz and tanzanite. Every one of them is treated, and in three cases the treatment is undetectable.
READ
Is tanzanite good for astrology? What the traditions say
No classical tradition assigns tanzanite anything, because the stone was unknown until 1967. What is documented, what is convention, and what is belief.
READ