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Royal Coster
Diamonds Size
MM / INCH (Circumference)
48 / 1.89 48 4½ 8
49 / 1.93 49 9
50 / 1.97 50 K 10
51 / 2.01 51 L 11
52 / 2.05 52 6 12
53 / 2.09 53 13
54 / 2.13 54 14
55 / 2.17 55 O 15
56 / 2.20 56 P 16
57 / 2.24 57 8 17
58 / 2.28 58 18
59 / 2.31 59 R 19
60 / 2.36 60 9 S 20

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Tanzanite, a rare gift of nature - Royal Coster Diamonds

Tanzanite, a rare gift of nature

Practical information about tanzanite

With a hardness of 6.5 on the Mohs scale is tanzanite suitable to wear in jewelry. But we recommend being careful to bump it. The gem can break or tear. If you want to clean your tanzanite jewelry, do so with lukewarm water, soap, and a soft toothbrush. But watch out! The gemstone damages easily by ultrasonic, steam cleaning or high temperature (enlarging/reducing a ring). So do not bring your jewelry to the first best jeweler or goldsmith! Only gemologists (gems experts) know what to do with your precious Tanzanite jewelry. rough piece of tanzanite

Know the rules of the rock

The GIA (International Gemological Institute of America) diamond assesses the four C's. Tanzanite also rates according to the stone's color, clarity, cutting, and carat. Of course, also here, the higher the combination of the 4C's, the rarer and more valuable the gemstone is.


Just like diamonds, tanzanites weigh in carat. 1 carat is 200mg. Gems with the same dimensions in width and length can have different weights, as the height of the gemstone is different. If the stone is so 'deep' than the carat weight will be higher.


The color determines the tanzanite's price. The intensity of the gemstone ranges from Vivid to Pale (V to P). This stands for the intensity of the existing colors of blue and violet. The deeper the color, the more valuable the tanzanite is. The color of the highest quality is sapphire-blue. In artificial light, the precious stone looks more like amethyst violet. After processing (heating and grinding), the stone can vary the color from beautiful deep blue to bright purple. tanzanite halo diamond earrings


The purity of the gem is expressed by flawlessness or clarity (loupe clean) to coarse inclusions (heavily included). Loupe clean means no visible inclusions (defects) are visible with a 10x loupe. Eye clean means that the stone has no visible inclusions visible to the naked eye. Tanzanite gemstones valued as lightly included have small inclusions visible to the naked eye. If the defects in the stone are larger and more noticeable, than its quality will be moderately included. More inclusions in the stone means the quality is "Heavily Included".


A better cut means a better sparkle. Therefore, it is wise to choose your gemstones at a renowned jeweler. A properly cut gem has the ideal proportions and symmetry. We call this an 'excellent cut'.

History of Tanzanite

550 million years ago, Tanzanite arose from the Mount Kilimanjaro in Tanzania. Yet the gemstone remained unknown to the public until 1967. The first time the gemstone surfaced, people were actually at the lookout for sapphire gemstones. The mineral Tanzanite belongs to the Zoisite group (named after the collector Baron von Zois). The bespoke gem was first discovered in 1805 on the Saualpe in Carinthia. It thanks its name to the original finding place, Saualpete. But only for a few decades, quality gemstones are known as Tanzanite, Thuliet, and Anyolite. Of the remaining transparent Zoisite varieties with gemstone quality (colorless, green, and brown) are so far only individual pieces or very small quantities well-known. tanzanite diamond halo ring

Fun fact

A fun fact is Tanzanite which owes its name to the New York jeweler Tiffany, who was looking for a beautiful and distinct name for this particular stone.


At Royal Coster, we also have a stunning collection of tanzanite jewelry. Discover our collection in our open showrooms, or contact a diamond consultant.
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