Japanese flag spinels with an unusual red core

As written in a previous post, as a spinel lover a bit “geeky” I have hand-selected all my spinel samples under a microscope… here are some photomicrographs of what I have been amazed to find in some samples selected from a spinel lot from Myanmar (Burma): some rare and natural bicolor spinels with a spherical bright red core right in their center!

Icing on the cake, those are twinned spinel crystals.

They are sometimes called “Japanese flag” spinels due to their resemblance to the national flag of Japan (a white banner bearing a crimson-red disc at its center).

The photomicrograph below shows a 0.21 ct bicolor “Japanese flag” spinel where it is also clear that all inclusions it contains (black crystals and whitish veils) are concentrated within the red area.

This photomicrograph below shows a 0.34 ct bicolor “Japanese flag” spinel where one can easily imagine why those amazing spinel crystals are sometimes called that way.

Here again, it is striking to see that all inclusions (mostly dark crystals) are again concentrated within the red area.

The reason why all inclusions tend to concentrate in the red area and the way this red core has formed are still unclear to me. As I couldn’t find any articles in the gemological literature on those two phenomenon, if you have some references or if you have any idea to explain one or both, please share with us in those post-related Facebook and Instagram conversations (link below).

Thanks in advance and see you there!

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