Star Spinel

[Starstruck8]

This is my star spinel. It is a bit more translucent than it looks in the picture. But In truth, it's more an interesting curiosity than a really attractive stone.

The cool feature of star spinel is that it has four star axes. The lower pic shows one of the off-centre stars. How does this work? Spinel has cubic crystal structure. The rutile inclusions are aligned to the octahedron edges. The resulting star axes are aligned to the four long diagonals of the cube.

If people have star spinels, I would be interested to see them. Especially if they are good translucent ones.

 

[Autumn in New England]

How cool... is the body black in person? Spinel is my favorite black stone. It's a true black, unlike diamond, it's not treated, unlike diamond, and it's still perfectly durable because it's typically inclusion-free.

In any event, here's a great article on star spinel. Very interesting! Apparently, they're quite uncommon. https://www.gia.edu/gems-gemology/summer-2018-microworld-star-spinel-with-four-and-six-rays

 

[Starstruck8]

How cool... is the body black in person? Spinel is my favorite black stone. It's a true black, unlike diamond, it's not treated, unlike diamond, and it's still perfectly durable because it's typically inclusion-free.

In any event, here's a great article on star spinel. Very interesting! Apparently, they're quite uncommon. https://www.gia.edu/gems-gemology/summer-2018-microworld-star-spinel-with-four-and-six-rays

The body is dark blue, a bit lighter than the photo. It's actually 'not unattractive'. But not remotely in the class of a good sapphire cab.

Yes, black spinel is an excellent black stone - better than onyx, because it's harder, takes better polish, and has higher RI, so gives sparklier reflections.

In my experience, opaque grey star spinels are available, and pretty inexpensive. But star spinels with any sort of translucency are hard to come by. That's why I was hoping some PSers might have some to show.

Thanks for the reference. My stone has the four-ray stars the article mentions. Actually, they are just the crossing points of the arms of the six-ray stars.