Color: Red, purple, blue, lavender, green, pink, yellow (unusual), orange/peach
Moh’s Hardness: 8
Refractive Index: 1.712-1.736
Critical Angle: 35.79°
Specific Gravity: 3.58-3.61
Fracture: Conchoidal, uneven
Heat Sensitivity: None
Birefringence (double refraction): None
Crystal Structure: Isometric
Treatments: Generally none
What I prefer to polishing with: Alumina oxide on a Tin lap, Spectra Ultralap, 8,000 diamond pre-polish 50,000 diamond polish on a Zinc laps
Jeff’s Comments: Spinels are easy to cut and come in about any color. Some rough has a grey under tone and I recommend against buying this type of rough. There are a few rare color change Spinels, but they are not common.
Design Notes: About any Spinel design will work well… As the rough gets more saturated I prefer checker board designs. For light rough I like deep brilliant designs.
Design Links: Cornered -This will work nicely in darker rough