Three large tanzanites sold at Bonhams for about $250 to $580 per carat, including premium. These are public results for stones above 25 carats, from 2010 and 2020, so they are reference points and not a current price list.
We found no reliable trade price list for tanzanite. Retail guides publish ranges that disagree widely, so this page keeps to named results and to what GIA says about value.
TL;DR
Tanzanite has only one source, according to GIA: the hills of Merelani in northern Tanzania.
GIA says deep saturated violet blue or blue violet are the most valuable colors, and that paler hues are more common.
GIA says tanzanite is often heated at low temperatures to remove a brownish color component.
A price for a cut stone and a price for rough are not comparable.
Tanzanite Price Per Carat: Public Results
Lot and source | Total, with premium | Per carat (our arithmetic) |
|---|---|---|
About 75.51 ct, intense bluish violet. Bonhams Los Angeles, Aug. 2020 | $43,825 | About $580 |
About 27.60 ct, very fine blue. Bonhams Los Angeles, Oct. 2020 | $13,512.50 | About $490 |
About 71.98 ct. Bonhams New York, May 2010 | $18,300 | About $250 |
None of these listings mentions a lab report or a treatment, and they are older sales. A smaller stone or a recent sale can price differently.
What Drives the Price of Tanzanite?
Color comes first. GIA says deep saturated violet blue or blue violet are the most valuable colors, while paler hues are more common. It also says eye-visible inclusions decrease value, particularly in lighter colored stones.
Size matters because of color. GIA says a gem must be above five carats in size to have fine color. We found no reliable public multiple for how price per carat rises with size, so we do not publish one.
Is Tanzanite Heat Treated?
Often, yes. GIA says tanzanite is often heated at low temperatures to remove a brownish color component and produce a stronger purplish-blue color. GIA also says tanzanite is pleochroic, so tilting a stone shows three distinct colors in three crystal directions.
Why Rough Prices Do Not Compare
In June 2020, Tanzanian miner Saniniu Laizer sold two rough stones of 9.27 kg and 5.1 kg to the Tanzanian government for about $3.35 million, according to reports citing the mining ministry. That works out to about $47 per carat across roughly 71,850 carats (our arithmetic). It is a price for uncut rough, sold to a state for preservation, and says little about what a cut stone costs.
How to Read a Tanzanite Quote
Check the color description against the stone. A grade from a seller is not a lab finding.
Compare inside the same size band. A price for a 2-carat stone and a 20-carat stone are different markets.
Separate the stone from the jewel. A ring price also pays for the mount and any diamonds.
Ask about treatment and durability. GIA gives tanzanite a Mohs hardness of 6 to 7, softer than ruby, sapphire or spinel.
To compare other reference stones, see Sapphire Price Per Carat and Ruby Price Per Carat.
FAQ
How much is tanzanite worth per carat? Public Bonhams results for stones above 25 carats ran from about $250 to $580 per carat, including premium, in sales from 2010 and 2020. We found no reliable public price list across all sizes and qualities.
Where does tanzanite come from? GIA says tanzanite has only one source, the hills of Merelani in northern Tanzania.
What color tanzanite is most valuable? Deep saturated violet blue or blue violet, according to GIA.
Is tanzanite a good investment? We do not give investment advice. A few auction results do not establish a reliable return.
Useful Sources
Carat Brief is editorial and is not investment advice. Get sourced gem prices, free, every Tuesday.