Why Is Tanzanite Rare
While man made tanzanites have flooded the market as a cheap replacement, the original natural tanzanite is rare as it is only available at the foothills of Mt. Kilimanjaro, a peak in Tanzania (East Africa). Mt. Kilimanjaro, famous also as it is the highest peak in the world when measured from sea-level, also being a lone volcanic mountain. Geologists have done extensive research and concluded that it is near impossible for such perfect geological, chemical or compositional elements to ever occur again in the same place, making this a one off occurrence and all the more precious.
Diamonds are a thousand times more easily available than tanzanites, plus they are higher on the Moh scale. Supplementing its rarity, the tanzanite isn’t very high up on the Moh scale which makes it easily breakable while mining and faceting. This makes it even harder for a high quality stone to come into the market.
Only less than 1% are organically heated by the earth’s temperatures to develop in those intense blue-purples that we cherish. The next most important factor in terms of rarity is the size of them. Let us say that the miner has crossed the barriers of finding tanzanites that are also naturally blue, what about how many carats the stone actually is? Often zoisite crystals will be brown or grey overall with slight tinges of blue or green, which isn’t good enough. So not only is finding a tanzanite itself infrequent, but also mining one of a reasonable size.
This factor has a great impact on price and value as carat is the most objective measure of a gemstone. For example a blue tanzanite which is two carats will not be double the price of a one carat tanzanite but rather four to five times. As the size of a tanzanite increases, so does its rarity and hence its price – not a proportionate increase but rather an exponential one.
The next time you have the opportunity to buy a tanzanite with such properties don’t turn it down!