What Exactly is "Red Flash" in Tanzanite?

Gems Jewelry Blog. October 2012 05:55

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 is one of the gem kingdom's only trichroic gemstones. As such it displays three different colors on three different axes.

Tanzanite's reddish violet axis is more visible in a warmer light whilst its blue axis is more visible in a cooler light. 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. 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.