Zultanite (color-change diaspore) and color-change pyrope-spessartine garnet are both moderately hard color-change gems but differ in mineral species, optical character, and per-carat price. Diaspore is biaxial positive with strong birefringence; garnet is singly refractive. Zultanite shifts sage-to-raspberry; garnet typically shifts blue-green-to-purple. Garnet trades at USD 200–2,500/ct; Zultanite at USD 750–14,000+/ct.

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.