Spessartite Garnet

Spessartite is the orange garnet, and at its best — the mandarin material — it is one of the few genuinely saturated oranges in gems. Color runs from a warm yellow-orange through to deep reddish orange.

Its refractive index is high for a garnet, so it keeps returning light under the dim indoor lighting where paler stones go lifeless. Mohs 7 to 7.5, no cleavage plane. Buy it for the color: there is no synthetic flooding this market, so what you are paying for is the saturation.