Tanzanite is a beautiful blue stone that is mined in Tanzania. It is a fairly rare stone because it exists naturally only in the mines in this country and is generally rather small in size. The stone tends to be relatively soft and cannot be worn on a daily basis, but it makes a stunning piece for formal wear for special occasions. If the situation should arise, read on to learn how to evaluate Tanzanite jewelry.
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Consider the color. Tanzanite comes in a wide gradient of blues that range from ultramarine to light violet. The most valuable color is a deep blue surrounded by a hint of violet. This type of coloring tends to only be visible in larger stones (eight carats or more) unless the stone has been treated to enhance the color.
Find out if the stone has been heat treated. Most Tanzanite gems have slightly brown or “muddy” portions. These can make the gem unattractive. However, the discoloration can be eliminated by heating the gem to very high temperatures. This does not have any detrimental effect on the gem, but some jewelry purists do not like to own stones that have been heat treated. If the stone has received this type of treatment, make sure that you are informed as the price should reflect the treatment.
Check the top surface for flaws. While interior inclusions do not usually affect the brilliance of colored gemstones, scratches on the top surface of the stone can make a gem look cloudy and less brilliant. Examine the top surface of the stone carefully and in several different lights to make sure that it is as bright as you desire.
Decide how you want to wear your gem. If you are going to wear your Tanzanite jewelry a lot, then you probably should buy earrings or a necklace rather than a ring. The setting should also reflect the way you want to wear the stone. Bezels provide more protection for a stone than prongs, and if you are buying a particularly large stone to wear frequently it should have six prongs instead of four.
Rate the size of the gemstone. Tanzanites generally are found in sizes between half a carat and three carats. However, the most valuable and beautiful cuts and colors in this stone are most evident when the stone in question is around 10 carats. You will need to decide how important a variety of colors in the same stone is to you when you are deciding what size stone to buy.