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Tanzanite · Zoisite · 6 to 7

Tanzanite

Tanzanite is the blue-violet variety of the mineral zoisite, and it is found in only one place on earth: the Merelani Hills of northern Tanzania, near Mount Kilimanjaro. It was discovered in 1967 and named by Tiffany & Co., which launched it in 1968. Most tanzanite comes out of the ground brownish and is heated to bring out the blue-violet, a standard, permanent treatment. Tanzanite is not grown in labs commercially, so anything sold as "lab tanzanite", "created tanzanite" or "nano tanzanite" is a different material made to look like it.

From the ground to your hand

The same stone at four moments. Tap a photo of a listing to see it on Amazon.

  1. 01 In the ground (step 1 of 4)

    A sharp, glassy tanzanite crystal, 9 cm tall, from the Merelani Hills, Tanzania, the only place tanzanite is mined.

    A sharp, glassy tanzanite crystal, 9 cm tall, from the Merelani Hills, Tanzania, the only place tanzanite is mined.

    Real specimen. Photo: Robert M. Lavinsky, CC BY-SA 3.0.

  2. 02 Cut (step 2 of 4)

    Rough and cut tanzanite side by side, both from the C-Block mine at Merelani.

    Rough and cut tanzanite side by side, both from the C-Block mine at Merelani.

    Real specimen. Photo: Didier Descouens, CC BY 3.0.

  3. 03 Rough to own (step 3 of 4)

    About 30 carats of natural tanzanite rough crystals.

    About 30 carats of natural tanzanite rough crystals.

    Amazon listing photo. See it on Amazon

  4. 04 Loose (step 4 of 4)

    A 6 mm round natural tanzanite, about 0.9 ct, AAAA grade, from Instagem.

    A 6 mm round natural tanzanite, about 0.9 ct, AAAA grade, from Instagem.

    Amazon listing photo. See it on Amazon

Mineral
Zoisite (calcium aluminium silicate)
Colour from
Trace vanadium; most stones are heated to turn brown to blue-violet
Hardness
6 to 7, softer than sapphire or topaz
Grown in labs?
Not commercially. "Lab tanzanite" is forsterite, lab sapphire, glass or cubic zirconia
Only source
Merelani Hills, Tanzania

Famous tanzanite in museums

What the finest natural stones look like: real pieces in public collections. The whole gem museum.

Tanzanite and white sapphire necklace: Designed and made by Ernesto Moreira in Houston in 2006: 16 graduated tanzanites totalling 208.85 carats with 17.5 carats of white sapphires, set in 18kt white gold.
Tanzanite and white sapphire necklaceDesigned and made by Ernesto Moreira in Houston in 2006: 16 graduated tanzanites totalling 208.85 carats with 17.5 carats of white sapphires, set in 18kt white gold.Houston Museum of Natural Science, TexasTanzanite comes from one mining area on earth, the Merelani Hills of Tanzania.Photo: Wikipedia Loves Art participant "Assignment_H, CC BY-SA 2.5.
Tanzanite at the Cleveland Museum of Natural History: A tanzanite on display in the museum gem gallery, photographed in 2014.
Tanzanite at the Cleveland Museum of Natural HistoryA tanzanite on display in the museum gem gallery, photographed in 2014.Cleveland Museum of Natural History, OhioTanzanite comes from one mining area on earth, the Merelani Hills of Tanzania.Photo: Tim Evanson, CC BY-SA 2.0.

Natural tanzanite vs the stones sold as "lab tanzanite"

Mined and lab-grown tanzanite are the same mineral; this is what differs
Natural tanzaniteSynthetic forsterite
What it isZoisite from the Merelani HillsA man-made crystal of a different mineral, reported by GIA as a tanzanite imitation in 1999
Colour as you turn itBlue, violet and burgundy (three colours)Can look close in a photo
Tell-tale signFaint doubling, no bubblesStrong doubling of the back facet edges under a loupe
PriceRoughly $100 to $500 a carat for good stones, more for top colourA few dollars a carat
How it is listedSays natural, names Tanzania or Merelani, gives weight and size"Tanzanite color", "simulated", sometimes no warning at all

Tanzanite comes from one small mining area, so it is never cheap. A "10 ct certified natural tanzanite" for $30 is not tanzanite. Real listings name the weight, the size in millimetres and Tanzania, and cost hundreds of dollars for a stone over a carat.

Treatments. Almost all tanzanite is heated to remove a brown tint and bring out the blue-violet. This is permanent and accepted. Some tanzanite has been coated with a thin cobalt-bearing film to deepen the colour; GIA found one such coating could be wiped off with a cleaning cloth. Avoid ultrasonic cleaners and sudden heat: tanzanite can crack. All gem treatments explained.

Where natural tanzanite comes from

Pins mark mining districts, not exact mines. Drag to move, pinch or scroll to zoom, tap a pin to read about it. Map data © OpenStreetMap contributors.

List of every place on the map (1)
  • Tanzanite: Merelani Hills, Tanzania. The only known source of tanzanite in the world.

How it is cut

Lab tanzanite is mostly machine-cut in calibrated sizes, which is why a cut lab stone costs little more than its rough. Fine mined stones are often native-cut to keep weight, then recut by precision cutters. See cuts from easiest to hardest and whether cutting your own is cheaper than buying cut.

What to buy

Checked in stock on October 10, 2026. Photos are the listings' own; prices are rounded.

Reading a gem listingGem treatments

The tanzanite shop: 20 more pieces we trust

Every piece names the real stone and comes from a seller with a record, checked in stock on October 11, 2026. Photos are the listings' own; prices are rounded.

Loose stones2.29 ctPUHARGEMS natural tanzanite, round, 8 mm, 2.29 ct, AIG reportA violet-blue stone with a lab report.about $870on Amazon →Loose stones2.17 ctPUHARGEMS Tanzanian tanzanite, oval, 9 x 7 mm, 2.17 ctabout $450on Amazon →Loose stones1.00 ctPUHARGEMS Tanzanian tanzanite, emerald cut, 7 x 5 mm, 1.00 ctabout $230on Amazon →Loose stonesInstagem natural tanzanite, round, 6 mm, AAAATop colour grade in a small size.about $180on Amazon →Loose stones1 ctInstagem natural tanzanite, oval step cut, 7.4 x 5.4 mm, about 1 ctabout $145on Amazon →Loose stonesInstagem natural tanzanite, marquise, 8 x 4 mmA starter-priced real tanzanite.about $70on Amazon →WomenGem Stone King natural tanzanite stud earrings, solid 14K goldabout $130on Amazon →Women1.00 ctGem Stone King tanzanite stud earrings, 5 mm, 1.00 ct total, sterling silverOver 200 ratings.about $57on Amazon →Women2.10 ctRoss-Simons tanzanite flower earrings, 2.10 ct total, sterling silverabout $140on Amazon →Women2.90 ctRoss-Simons tanzanite flower ring, 2.90 ct total, sterling silverabout $160on Amazon →Women3.70 ctRoss-Simons tanzanite inside-outside hoop earrings, 3.70 ct total, 18kt gold over silverabout $200on Amazon →Women0.40 ctRoss-Simons 0.40 ct tanzanite and white zircon ring, 18kt gold over silverabout $95on Amazon →

Your kit for tanzanite

Five tools that let you check what you bought (a loupe, a UV torch, locking tweezers, a gem box and a pocket scale), plus a turntable that spins your stone under the light the way jewellers show one. The full collector's kit.

LookGemOro 10x triplet loupeunder $20LookDARKBEAM filtered 365 nm UV flashlightabout $10HandleHonoson locking tweezers, 3 packabout $10StoreTeensery gem display boxes with clear lids, 10 packabout $9ShowComXim motorized turntable, adjustable speed and directionabout $15MeasureGemOro Platinum XP500 pocket scale, 0.01 gabout $40

In short

Tanzanite grows over millions of years in the earth, or in hours to months in a lab. Both are real tanzanite; the mined stone is rare and priced for rarity, the lab stone is priced for the cost of growing it. Buy lab to wear and enjoy, check the listing names the mineral, and test it when it arrives.

See our first pick: Instagem natural tanzanite, oval, 8.5 x 6.5 mm, about 1.2 to 1.75 ct

Frequently Asked Questions

Is there lab-grown tanzanite?

Not in jewellery. Listings called "lab tanzanite", "created tanzanite" or "nano tanzanite" are other materials: synthetic forsterite, lab-grown sapphire, cubic zirconia or glass. They can be pretty and cheap, but they are not tanzanite.

Is tanzanite heat treated?

Almost always. Most rough is brownish and is heated to bring out the blue-violet. The change is permanent and is standard in the trade.

Is tanzanite only found in one place?

Yes. All gem tanzanite comes from the Merelani Hills in the Arusha Region of northern Tanzania, near Mount Kilimanjaro.

Is tanzanite good for an everyday ring?

With care. At 6 to 7 on the Mohs scale it scratches more easily than sapphire, and it can crack from a hard knock or sudden heat. Earrings and pendants suit it best; for a ring, choose a protective setting.

Photo credits

  • zoisite-tanzanite-tanzaniab.webp: Robert M. Lavinsky, CC BY-SA 3.0, via Wikimedia Commons.
  • zo-site-tanzanite.webp: Didier Descouens, CC BY 3.0, via Wikimedia Commons.
  • Product photos: Amazon listings, via the Amazon Product Advertising (Creators) API.

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