Star of David spinel formations are exceedingly rare, but even more so when found in matrix like the specimen pictured above. Only one other such formation is known to exist; all other crossed penetration twin specimens found to date have been alluvial.

A textbook example of an octahedral spinel formation. This example is a Jedi, bearing the almost fluorescent color that gives Jedis their name.

The Star of David formation in spinel gems is a source of fascination for gemologists and collectors. The study of these rare specimens contributes to our understanding of spinel crystal formation and to the determination of origin. When gemology students initially learn about spinel, they are taught to look for octahedral crystals – a crystalline formation that resembles two pyramids stacked end to end. The shape is present in both the external spinel crystal formation and in the smaller microscopic formations found inside the gemstone.

This formation shape occurs because spinel belongs to the cubic crystal system. In rare cases, a twin plane develops that alters the overall shape of the stone. The twin plane emerges in parallel to the octahedron, and the twin is formed by a rotation of one part of the crystal through 180 degrees about a triad axis (GIA, “Star of David” Spinel Twin Crystal with Multiphase Inclusions from Mogok). The phenomenon is called the “Spinel Law” because it is most commonly seen in spinel crystals, but the same phenomenon is responsible for the formation of diamond crystals commonly known as “macles”.

A close up view of the stunningly rare specimen.

Star of David spinel crystals are most commonly found in Pein Pyit, a mining region on the eastern border of Mogok, Myanmar. The area is famous for twinned Star of David spinel crystals (hundreds were discovered in the area in the early 2000’s, though most were small or broken), but they are never found in the marble host rock due to a combination of the way spinel is mined and the rarity of the occurrence itself.

This particular specimen only occurs in a single pocket in Pein Pyit. Pockets can be incredibly short lived, so this may very easily be the only intact specimen recovered from the site. The specimen dimensions are 60.13 x 46.18mm, with the xtal presenting at approximately 6mm, a large size for gem quality specimens of this type. The discovery makes an important contribution to the body of knowledge available concerning these rare, spectacular formations.