Zultanite (color-change diaspore, 6.5–7 Mohs, RI 1.682–1.752) and color-change sapphire (corundum, 9 Mohs, RI 1.762–1.770) differ in hardness, durability, optical character, and color-shift register. Sapphire shifts blue-to-purple/violet; Zultanite shifts sage-to-raspberry through a champagne-gold mid-phase. Sapphire is more durable for daily-wear jewelry. Synthetic color-change sapphire is widely traded; Zultanite has no commercial synthetic.

Mineralogy

Each gem is identified by its mineral species, hardness, refractive index, and optical character. The verified values are documented in the property guides.

Optical phenomenon

The two gems compared here differ in the physics of their optical drama. Color change depends on illuminant; other phenomena depend on structure or viewing angle.

Source and supply

Where each gem is mined and how supply is structured determines availability and price stability.

Jewelry suitability

Hardness, cleavage, and toughness govern which gem suits ring-grade vs occasional-wear jewelry.