GIA tells us that Spinel, like garnet and diamond, is singly refractive, with the same physical properties in all crystal directions. It belongs to the cubic crystal system, and its characteristic crystal shape is an octahedron, which looks like two back-to-back pyramids. Well-formed spinel crystals are fairly common in nature.
The color was the primary importance for AGBF, and I am so glad she stuck to her guns about it. What makes jewelry so magical is it’s importance  and significance to the individual (the fact that it is also beautiful is fabulous icing on a spectacular cake)!
Safe at home, at last!
Love it, congratulations on your ring creation success story! I hope it’s continued to bring joy in the intervening years!
The Stats:
Spinel Center Stone:
3.16 carats.
10.24mm x 8.25mm x 4.91mm.
It originated in Myanmar (Burma).
untreated
Color description: red
Shape: cushion
Cutting style: mixed cut
Cutting grade: very good to good (4-5)
Finish grade: very good to good (4-5)
Color grade: 2.5/80
Clarity grade: LI1 (lightly included)
Total quality: excellent to very good
The side stones are a .51 and a .53 carat D colored VVS2 pear shaped diamonds