Judging Tanzanite Color can be a confusing undertaking, especially online. This article will demonstrate Tanzanite color qualities in straightforward terms without the jargon.
GIA Graduate Gemologist
ICA Ambassador to Kenya
The adage “color is king” applies to Tanzanite, just as it does to all colored gemstones. It is the single most important value factor. When talking about Ruby, you hear descriptions like “pigeon’s blood red” to describe the deepest, most valuable colors and with Sapphire you hear “cornflower blue” to describe the finest Sapphire colors, generally from the ancient Kashmir deposit.
Tanzanite is no different and color plays a large part in any grading exercise. The rules of color generally follow the laws of nature in that strong, vivid colors are attractors. Humans, for centuries have gravitated towards the deepest colors in gemstones, it is part of our psyche. This has been translated into a value system for gemstones, Tanzanite included, whereby the most vivid and deeply saturated colors are more highly coveted.
Color – What to look for in the Finest Grade
Whilst color grading systems can appear very complicated and
technical, I am not going to go into actual grading systems in this article.
Grading systems can confuse the issue as there are so many approaches these
days notwithstanding the many invented ones that are prevalent on the web now
where it seems that the more plus (+) signs you add to a made up grade or the
more A's, the more accurate the grade! We have a separate article which goes
into grading systems in depth if you want to learn more about those -
Tanzanite Color Grading Systems Article.
Without the smoke and mirrors of grading systems, the
mechanics of color are actually very simple and for the purposes of this
article we will not go into technical details as these have been covered
separately in the above article. We will simply explore what it is you need to
be looking for in a fine Tanzanite in terms of color, look at some videos and a
color chart and this should be a good grounding in getting you to a
knowledgeable position on Tanzanite color.
Color Saturations and how they Relate to Rarity
Saturation is basically the depth of color in a stone, in
essence the level to which color “fills” the stone. The more saturated a color
is in a Tanzanite, the more valuable. This is not only because humans generally
gravitate towards the more vivid colors but also because they occur much more
rarely in nature. In fact, in the very finest 1% grades, very few carats are
mined a year. The video below shows what these very fine stones look like.
Video of Fine Tanzanite Colors. Tanzanites from our
As you will see from the video, these stones have a very
vivid, extremely intense color. This is because their color saturations are
very high. As this color saturation
drops and the stones lose the intensity of the color, the grade drops in
Take a look at this simple chart below to see how as
saturation decreases, so does the grade.
In terms of rarity, the very fine colors shown in the video
represent less than 1% of Tanzanite production. Miners used to use the term AAA
to describe these pieces but honestly, this term seems to have lost most of its
meaning as a quick search online will show you a huge quantity of sellers all
calling their merchandise AAA, AAAA or adding a profusion of plus (+) marks to
them to make them more marketable despite the fact that the color is clearly
nowhere near the finest grades.
The fact is, these top colors are very rare and
do not occur in large quantities. Most sellers are selling stones in
the B, A or AA grades and spike the images to improve the appearance.
A video is a much better medium in which to judge color as it displays
color more fully without interference you can see the stone from different
angles and judge it in a more objective manner.
Tone and its Part in Tanzanite Color
Tone also plays a part. Tone is covered more deeply in our
article on Tanzanite Grading systems under the GIA grading system section as
this system is the more advanced and looks at all facets of color. However for
the purposes of this article, a good description of Tone is the lightness to
darkness of a stone.
This is not actually describing the color saturation itself
but rather overall tone and the light extinction within the stone. Bad cuts can
play a part here as bulged pavilions (backs) cut to maximize weight can
increase tone and make a stone look dark to an untrained eye so be aware of the
role of cut (our article on Tanzanite Cut is very informative on this subject).
Always examine the areas where light reflects within a stone and examine it for
its true color rather than being blinded by dark areas caused by light
extinction. A stone that is dark because of overly high levels of tone is not
the same as a Tanzanite that is highly saturated. In fact you can get very dark
looking Tanzanites with high tone levels which have low color saturations.
These are certainly not top grade pieces. If you look at this chart you will
see how this works.
You can see how a Tanzanite can look dark with low
saturation levels but high tone levels. This is not the same as top grade
stones which have optimal mixes of tone and saturation. The very finest grade
shown demonstrates how intense saturation can go.
The Role of Trichroism in Tanzanite Color
Any discussion of color would not be complete without a
mention of trichroism. Tanzanite is not a simple stone in any respect but when
it comes to color, it has a kicker – it is trichroic. Trichroism is a
gemologist’s term which means that as light passes through a mineral it
vibrates in different planes. This causes the stone to exhibit a different
color depending on which axis you are looking at it from. This phenomenon makes
Tanzanite very reactive to the light source under which it is viewed. Whereas
trichroism does not impact on Tanzanite's grade or value, it is an inherent
part of Tanzanite's color so we thought it important to touch on the subject
here. This article Trichroism and Red Flash in Tanzanite goes into some depth on this.
Putting it All Together
Tanzanite value, as with all colored gems, is largely linked
to its color. The deepest, most vivid colors are also the most rarely occurring
in nature. Online, this is not the case with almost every seller branding their
goods as the best you can find, and some selling at very low prices. Bear in
mind that the finest Tanzanites are mined very rarely and the miners demand top
dollar for them, they know the value of the few crystals of this grade they
mine annually. They are not widely available, nor do they go cheap. The
old adage, “…if the price is too good, then what is wrong?” should spring to
Approach your assessment of color simply – Examine
saturation levels and tone levels. The best medium to look at color is a video.
If there is a video, examine the color
closely and watch the saturation levels in a stone. Keep an eye out for light
extinction due to bad cutting.
This series of GIA Gemologist written articles on Tanzanite
is provided to create a greater understanding of Tanzanite value and
quality in the face of increased misinformation on the internet today.
ABOUT THE AUTHOR Antony Zagoritis, Bsc, GG
Antony completed his GG (Graduate Gemologist) in 1998 at the Gemological Institute of America in California after a degree a Business at the University of Bath, in England. He has extensive experience in the colored gemstone trade with over 20 years buying rough at the source. He is currently the Ambassador to Kenya for the ICA (International Colored Gemstone Association) in New York which is the worldwide body for colored gemstones.
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