{"id":35931,"date":"2026-10-20T05:45:02","date_gmt":"2026-10-20T05:45:02","guid":{"rendered":"https:\/\/4cminerals.cz\/?p=35931"},"modified":"2026-10-24T06:03:02","modified_gmt":"2026-10-24T06:03:02","slug":"tanzanite-how-to-choose-ring-necklace","status":"publish","type":"post","link":"https:\/\/4cminerals.cz\/en\/tanzanite-how-to-choose-ring-necklace\/","title":{"rendered":"Tanzanite: A Stone from a Single Deposit in the World. How to Choose a Ring or Necklace and How to Care for It"},"content":{"rendered":"\n

Tanzanite is one of the youngest gemstones on the market. Just sixty years ago it was not known as a gemstone, and to this day it is commercially mined in only one place in the world. It captivates with its rich blue-violet colour, which changes with the viewing angle and with the light. We explain where tanzanite comes from, why almost every stone has been heat-treated, what determines its quality and price, whether it is suitable for a ring and how to care for it.<\/strong><\/p>\n\n\n\n

A gemstone that no one knew sixty years ago<\/h2>\n\n\n\n

In 1967, a Maasai herdsman found blue-violet crystals in the Merelani area in northern Tanzania. He pointed them out to a local gem prospector, Manuel d’Souza, who registered the first four mining claims at the site. Within a short time, another ninety were established on the same territory of roughly 50 km\u00b2.<\/p>\n\n\n\n

The stone was named by Tiffany & Co., which became its main distributor. It named it after its country of origin and launched it on the market in 1968 with a major advertising campaign.<\/p>\n\n\n\n

Mineralogically, tanzanite is the blue-violet variety of the mineral zoisite. It is commercially mined in only one place in the world, the Merelani area near Kilimanjaro. It is precisely this uniqueness of the locality that is part of its appeal.<\/p>\n\n\n\n

Tanzanite is also one of the stones associated with December, making it a natural choice for December birthdays or as a Christmas gift. You will find tips on choosing a gift in our article A Gift with a Genuine Stone: How to Choose Jewellery That Lasts for Generations<\/a>.<\/p>\n\n\n\n

Why tanzanite changes colour<\/h2>\n\n\n\n

Tanzanite is strongly pleochroic<\/strong>: viewed from different directions, it shows different colours. For untreated tanzanite, the technical literature describes three colours: reddish violet, deep blue and yellowish green. The cutter must therefore orient the stone so that the desired colour stands out when viewed from above. Cutting for pure blue costs more rough material than cutting for blue-violet, and this is one of the reasons why pure blue stones are more expensive.<\/p>\n\n\n\n

Light also affects the colour of tanzanite. Cooler daylight<\/strong> emphasises blue, while warmer artificial light<\/strong> shifts the stone towards violet. The very same ring can therefore look like a sapphire by the window and like an amethyst under a lamp in the evening. When choosing, it is worth looking at the stone in both types of light.<\/p>\n\n\n\n

Heat treatment: common and stable<\/h2>\n\n\n\n

Most of the mined material tends to be brownish or has a yellowish-green component. Routine heating removes it and emphasises the blue and violet colour. This treatment is standard for tanzanite, is stable and, according to GIA, does not affect the durability of the stone. Heat-treated tanzanite is therefore the normal state, not a defect.<\/p>\n\n\n\n

Other treatments are rare, but it is good to know about them:<\/p>\n\n\n\n