What Exactly is "Red Flash" in Tanzanite?

One of the most common questions we get in our award winning “Ask a Gemologist” panel is “what is red flash in tanzanite and is it important? Many jewelers today are using the phenomenon to promote the “mood changing” abilities of Tanzanite and the phrase is now in the public domain in a big way. Many people are confused by the terminology or simply disappointed if a Tanzanite they have purchased seemed to have plenty of red flash in the jeweler’s store but none when they are looking at it at home.  

Red Flash is simply a function of Tanzanite’s trichroism. To explain further – Tanzanite os one of the gem kingdom’s only trichroic gemstones. As such it displays three different colors on three different axes. This article in our article center goes into much more depth on this   

Tanzanite’s reddish violet axis is more visible in a warmer light whilst its blue axis is more visible in a cooler light. This article explains how light works in gems for a better understanding of the issue.   

The result is that under a warm light source Tanzanite displays a much more violet hue with “flashes” of red and pink coming from the violet axis. All Tanzanite has this phenomenon and it does not affect its value in any way. As a rule, the deeper the color saturation of the stone, the more pronounced is the red flash effect.  

Lapigems Gem Company

Comments (1) -

  • Thank you very much for this insight. I have 3 Tanzanites and love the red flash in them but have never had a clue as to what caused it. Very interesting. I have sent a few more questions to your Gemologists on your Ask a Gemologist panel related to this and am looking forward to learning more once the answers come back!
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