What is the most expensive color of tanzanite?

The incredibly beautiful, rich violet-blue colors of tanzanite have made this stone one of the most popular colored stones in recent times. Found only in Tanzania near the city of Arusha, tanzanite may not be that rare in terms of the number of stones mined, but it is rare in that it is not available in sufficient quantities to market. Tanzanite is a stone thousands of times rarer than a diamond, and unlike diamonds, of which deposits are constantly being found, tanzanite (at least for now) has only one deposit, which is already approaching depletion. According to geologists’ estimates made in 2009, the last raw tanzanite will be mined no later than in 15-25 years! Gemological information:
Color range: blue, violet, green, pink, yellow, brown, purple
Refractive index: 1.688 – 1.707
Chemical composition: Ca2(Al,OH)Al2(SIO4)
Hardness: 6-7
Density: 3.30 (+0.10, -0.10)
Crystal structure: Rhombic
Origin: Tanzania Upon its discovery in 1967, tanzanite was hailed by experts as the “gem of the 20th century.” They literally held their breath when they saw the first deep blue crystals found in Arusha, northern Tanzania. Over millions of years, metamorphic schists, gneisses and quartzites formed the spectacular mesa. It is inside these elevations that the precious crystals are hidden. For a long time they remained hidden from the eyes of people, until one day the Massai shepherds noticed the crystals sparkling in the sun and took them with them. Tanzanite is a variety of the mineral zoisite, which has blue, violet or purple hues in its trichroic range. This Ca–Al silicate with a hardness of 6 to 7 on the Mohs scale is not that hard. Therefore, you should wear it in jewelry with care, and never clean it using ultrasonic devices or using any abrasive materials. Tanzanites “do not like” contact with acids. After the famous New York jeweler Tiffany was offered the first tanzanites found, he was convinced: this gemstone was a real sensation! Tiffany suggested calling it by a different name, since the gemologically correct name “blue zoisite” was very reminiscent of the English word “suicide”, which is consonant with the word “suicide”. His proposal to name the stone “Tanzanite” after the place where it was found, quickly gained its place in the trade. A large advertising campaign made it possible, within two years after its discovery, to introduce the whole world to this delightful gem. Today the name “tanzanite” is officially recognized not only as a trade term, but also as a gemological term. In the first decade after the discovery of tanzanite, it was mined from the surface layers of the soil, which was dug to a depth of up to a meter and simply sifted. Gradually, “surface” mining came to naught, and prospectors began to dig not along, but in depth. And here a strange pattern emerged: the deeper the crystal was in the ground, the less and less blue it turned out to be. At a depth of 10 meters, at best, only green stones are found. It was then that the technology for thermal refining of tanzanites was developed. Although unheated crystals can be green, purple, yellowish or light blue, the brownish “beer” color is most characteristic of stones raised from a relative “depth”. Heating to 380 degrees Celsius results in an intense sapphire blue color. Amazingly, dark brown crystals turn into the most valuable dark blue stones when heated. The color and clarity are consistent after processing and the method is accepted by the gemological community. Unrefined faceted tanzanite, material from great depth Tanzanite is a trichroic stone and shows consistent strong pleochroism. The primary colors corresponding to the three optical axes of heat-treated tanzanite are “sapphire” blue, dark green and violet (extremely purple). Correct spatial orientation is the most important aspect and the most difficult problem when cutting, since it is necessary to take into account in advance the propagation of light in each of the three directions. Due to their similarity in color, comparisons between tanzanite and sapphire are inevitable. In terms of purity, tanzanites generally rank significantly higher than sapphires. However, tanzanites do not have the hardness of sapphires. The most valuable colored sapphires are rarer, denser, harder, and much more expensive. Historical tanzanite prices have shown surprising volatility and fluctuations. Wholesale prices for these stones have fluctuated between $15 and $1000/carat over the past 20 years. A function of supply and demand, tanzanite prices, once high, have never fallen too low due to the beautiful color, clarity and lack of availability of these gemstones. The color variety of tanzanites is actually very large! The lack of popularity of tanzanites of “fancy” colors is solely a consequence of the popularity and hype of tanzanites of “classic” shades. All images presented in the selection are photographs of real natural tanzanites that have undergone thermal treatment. This procedure does not always and does not necessarily transform tanzanites into stones with the most popular shades! Tanzanite Appraisal It is customary to evaluate tanzanite by color, size, quality of stone and clarity. Moreover, the degree of importance of the assessment parameters follows exactly in the specified order. Color is the most important factor in determining value. Most experts believe that the color price component of a stone is in the range of 50 – 70% of its total cost. Bright, intense, saturated tones are considered the best. The height of tanzanite perfection is bright violet-blue or blue-violet colors. Tanzanites can be too light or too dark, with medium-colored stones being most prized. Some dealers describe the best tanzanite colors as AAA. But the most reliable description of the color of tanzanite is in accordance with the GIA color scale. Based on a study of demand, GIA experts compiled a rating of the value of tanzanite flowers. Naturally, this rating is not an absolute and fixed value, but nevertheless, you can rely on it when choosing tanzanite. The rating list ranks the tanzanite colors in the following order (rating factors 1-10): – vB 6/5 – 10 (Highly saturated medium dark violet blue)
– bV 6/5 – 8.1 (Highly saturated medium dark bluish violet)
– B 6/5 – 8.1 (Highly saturated medium dark blue)
– vB 5/5 – 6.4 (Highly saturated medium violet blue)
– V 6/4 – 6.4 (Medium saturated medium dark violet)
– vB 7/5 – 6.4 (Highly saturated dark violet blue) – shown in the first photo And the list goes on. But as always, the most important factor when choosing the color of tanzanite is personal taste. The most beautiful tanzanite is the one that you like the most! IMPORTANT. DON’T LET YOURSELF BE FOOLED. Tanzanite is a rare enough and expensive stone that you don’t have to buy it anywhere or from anyone. There are far more tanzanites offered for sale on the market today than have ever been mined. Various counterfeits appear, from glass to painted quartz. There are a lot of options for “deceptions”, and therefore we must always remember the main thing: it is better to trust a specialist than an amateur. Tanzanites are occasionally found on sale that have not been subjected to heat treatment. They usually have very beautiful colors – green, yellow, pink, brown. Color saturation is generally extremely weak. Among such infrequently encountered “unheated” tanzanites, blue-violet ones are an exceptional rarity; their cost is an order of magnitude higher than a similar “heated” one and is comparable to the cost of a sapphire of similar size. Distinguishing unheated blue or purple tanzanite from heated one is sometimes easy, and sometimes almost impossible, unless sophisticated methods of physical or chemical analysis are used. Tanzanite is a trichroic stone. When heated, tanzanite will show blue, “matte” green and purple colors along different optical axes. Unheated tanzanite along one of the axes (which one depends on how the stone is cut) will certainly show a brown or yellow color, even if from the table the stone looks completely uniformly blue or purple. Unheated tanzanites of blue or violet color are almost always quite light, if the stone has such a color of intense saturated dark tones – the probability of “heating” tends to 100%. But it should be taken into account that the brown tint is not always removed from thermally treated tanzanites! In other words, a brown tint noticeable when observing pleochroism does not prove that tanzanite is not refined, but its absence proves that the stone is refined. Photographing tanzanite is no easy task! In order for the photograph to convey its true color, you can use only daylight “cold” light. Artificial lighting significantly enhances the violet component of the color, which is what many not-so-scrupulous sellers take advantage of. Tanzanite is a magnificent gemstone that, in a relatively short time since the discovery of the only deposit in the world, has found a place in the hearts of thousands of people and its niche in the gem market. This circumstance was facilitated by its unconditional beauty and rarity, as well as the fact that of all known gems, it is natural blue tanzanite that is most similar to sapphire – a favorite of all times. In this guide, we decided to address the questions of how to choose a good piece of jewelry and how much such a stone costs. To do this, consider the main parameters for assessing tanzanite. The content of the article:

Colours

First, let’s figure out what colors tanzanites come in. Tanzanite is a transparent jewelry variety of the mineral zoisite. Its color is due to impurities of various chemical elements, which is why it is so diverse, for example, iron and chromium contribute to the green color, manganese – pinkish, vanadium – blue. The classic color of tanzanite is violet-blue, with variations towards violet or blue, from light blue and lavender tones to dark blue and deep purple. Rare colors of jewelry zoisite are pink, green, yellow, and lavender. The most valuable is the rich blue, sapphire color of tanzanite, with a small content of violet (Vivid violetish blue). Pictured: blue-violet tanzanite For a long time, tanzanite was considered by buyers and jewelers as a rare natural imitation of natural sapphire, so a line of colors close to commercial varieties of sapphires is still in demand, for example, cornflower (cornflower blue), vivid (royal) blue – saturated blue, intense – intense blue . But all blue tanzanites contain violet to one degree or another. Separately, it is worth mentioning the most beautiful and amazing polychrome specimens; they are also called multi-colored; one such specimen contains 2-3 shades at once. For example, blue, green and purple. This distribution of shades is caused by two reasons that can be present simultaneously: crystal zoning and strong pleochroism, and their combination. Pleochroism is the property of a crystal to show different shades in different directions. It is present to varying degrees in many minerals, but in tanzanites it is very pronounced. The main advantage is that each such specimen is essentially unique and individual, since there are no two identically colored stones. If the crystal falls into the hands of a high-level specialist, polychrome tanzanite incredibly reveals its beauty, sometimes giving birth to amazing palettes. In the photo: a set of polychrome colored tanzanites Such multi-colored colors are extremely rare in precious and semi-precious stones, which makes tanzanites truly non-trivial. But it happens that in some multi-colored tanzanites the overall perception of color becomes inexpressive, since the shades, overlapping each other and reflected in the facets of the stone, are mixed, as if aimlessly spreading watercolor paints of several colors on a sheet of paper.

Ennobling

In nature, transparent zoisites are mined mainly with a brownish or greenish color. Commercially attractive colors are obtained through a heat treatment process. This is a common practice for improving color, and the fact that tanzanites are heat treated does not usually affect the value of tanzanites. Keep in mind that most blue and blue-violet tanzanites are heated. At the same time, many laboratories do not have methods that can unambiguously confirm or refute warmness. Conversely, it is generally accepted that polychrome tanzanites, in which three shades are observed, are unheated. Therefore, if the natural origin of tanzanite color is fundamental to you, pay attention to multi-colored zoisite jewelry.

Weight

The weight of tanzanites, like other stones, is measured in carats (ct). The cost of a carat directly depends on the weight, that is, as the weight of tanzanite increases, the price increases. They are cut for coating and sorted by size, shade and quality. Mostly these are light bluish and bluish stones, with a purple or lavender tint. Stones up to 2-3 carats are cut into standard shapes and sizes. Tanzanites larger than 3 carats are considered individual stones and are used for making piece jewelry. As the mass increases, the stones become more saturated, large ones look dark blue and dark purple.

Cleanliness

The majority of tanzanites are gem quality and of high purity. Therefore, samples with visible inclusions are valued much cheaper than visually clean ones. The most valuable are those that are visually clean (eye clean, vvs) and with inclusions barely visible to the eye (vs – very small inclusions). For stones with inclusions, the cabochon cut is most advantageous. Also, such tanzanites are a popular material for artistic stone carving.

Cutting

Transparent tanzanites are given various shapes: oval, cushions of different silhouettes (square, rectangular, more or less round), pear. Other cuts: step (baguette, octagon), marquise, circle, trillion – are less common. There is an unspoken fashion trend – heart-cut tanzanites, similar to the stone from the film “Titanic” directed by James Cameron. For such an idea, they often choose the shape of a wide pear, close to the heart cut, only without the characteristic depression (“slot”). Fancy cut is extremely rare. For tanzanites, the selection of pairs and sets is relevant. This is especially true for large blue and blue-violet (larger than 7 carats) specimens. This is due to the fact that tanzanites of this level are considered premium stones by default; in their price range they are valued as bright rubellites. Such pairs, as a rule, are immediately cut as a pair, achieving almost identical sizes, symmetry and proportions, therefore losses during cutting are significantly higher than when processing single stones, for which the principle of achieving maximum yield applies. It is also important to orient the crystal when cutting so that the blue color is as bright as possible. Therefore, there is a markup of 10% or more on tanzanite pairs, depending on production costs.

How to distinguish tanzanite from a fake

• Glass
• Sitall
• Synthetic corundum
• Synthetic spinel

If a buyer has any doubts about whether a stone is real, we recommend contacting a reputable gemological laboratory. You will receive a certificate or expert opinion describing the main characteristics and confirming its natural origin.

Tanzanites can be similar to other natural blue stones: sapphire, indigolite tourmaline, cordierite, zircon.

In the photo: an example of an examination report for tanzanite

Evaluation

To illustrate the question “how much does 1 carat of tanzanite cost”, let’s give an example.

Let’s consider specimens of natural origin of different weights, with the most sought-after characteristics: the shade is intense violet-blue (Intense violetish blue), visually pure, with a good Asian cut. The price of tanzanite will be:

• 5 carats – from 300-320 dollars per carat
• 10 carats – from 430-450 dollars per carat
• 15 carats – from 500 dollars per carat

Keep in mind that more saturated tanzanites (Vivid and Exceptional grades) are priced more expensive, while lighter tanzanites are cheaper.

If a stone has a European quality cut, excellent polish, arch and symmetry, the stone will be valued 20-30% higher. Conversely, obvious violations in the proportions of the crown and pavilion ratio, leading to the appearance of a “window” or deterioration in play, reduce the price of a tanzanite carat. A bluer color is valued higher, a more pronounced purple color lowers the value.

Tanzanite can be considered either a precious stone or a semi-precious stone, depending on which system the gem is considered in. Precious from the point of view of the international gemological community, semi-precious from the point of view of the legal approach.

You can choose your stone in the Gem Lovers catalog.