good morning.
This is Nori-chan, a GTJ staff member.
I also want to change and evolve.
In early October 2024, we suddenly introduced several zircons that appeared to be a mixture of bright blue and green.
At first, he said, "I bought it because I was attracted by its bright, mysterious and beautiful color." However, he discovered that it underwent an interesting change when exposed to UV light during photography, a process that is carried out before it is sold as a product. This is the change in the color of the base, which is the subject of this article, and is commonly known as the "tenebressence effect."
Tenebrescence (photochromism) is an optical effect in which the color of a mineral changes as it absorbs long-wave ultraviolet light. A typical example is hackmanite, which absorbs long-wave ultraviolet light and turns deep purple, then gradually returns to its original color. (※1)
This time, I will write about blue zircon that I purchased a while ago, and it is not a specialized article about mineralogy or the like, but rather an article with the purpose of observing minerals, like an experiment that anyone can do if they have the equipment.
This zircon was one of several introduced during the live show. The zircon's body color is a pale brownish blue. (※2)
UV light is applied. It is irradiated for about 1 minute during live performances. This UV light is designed to block visible light, so you can feel a significant change even after 10 seconds.
After about a minute of exposure to long-wave UV rays, the color has turned dark brown. The blue has disappeared quite clearly, and the brown has become more prominent.
It feels like the zircon, which is brownish blue (light blue) with a metallic luster, has changed color to a very solid brown zircon. The color change is more noticeable than I expected, but because the original color contains a blue tint, the difference in color change before and after is more clearly visible.
There is currently no mention of "tenebressence" in the EGL sorting. However, since there have been so many changes, I took the opportunity to request an identification certificate from the Japan-Germany Gemological Institute.
