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Quartz

Aventurine

Spangled green (most common), also orange-red and blue-grey varieties

Blue Green Red
Optical properties

Optical characteristics

Ref. index
1.544 – 1.553
Birefringence
0.009
Luster
Vitreous to waxy with aventurescence
Pleochroism
None None; metallic glitter is aventurescence from reflective mineral inclusions, not pleochroism.
Fluorescence
Inert.
Origins

Source localities

Russia Russia: Ural Mountains / Siberia
Significant

Classic source for alexandrite, demantoid, diamond and nephrite.

15% est. supply
Brazil Brazil: Minas Gerais / Paraíba / Bahia
Significant

Major source for beryl, tourmaline, quartz, topaz, chrysoberyl and rare minerals.

20% est. supply
India India: Rajasthan / Odisha / Karnataka
Significant ★ Top Source

Historic and modern source for garnet, moonstone, corundum and other gems; India produces the majority of commercial aventurine.

40% est. supply
China China: Xinjiang / Yunnan / Hubei
Commercial

Known for jade, turquoise, quartz and multiple gem deposits.

15% est. supply
United States USA: major gem fields
Commercial

Diverse sources for turquoise, tourmaline, opal, sapphire, topaz, red beryl and rare minerals.

10% est. supply
Treatments

Enhancement & treatment

Color Enhancement Dyeing Dyeing artificially improves color in porous or fractured materials. Durability varies and disclosure is…
Inclusions

Inclusions & features

Clouds Pinpoint Clouds Under 10x loupe: concentrations of extremely tiny bright dots that individually are too small… Zoning Color Zoning Under 10x loupe in immersion: bands or patches of deeper or lighter color arranged…
Identification

Instruments used

10x Loupe Your most-used instrument, start every examination here High CRI Penlight Tiny concentrated white spot for field checks, inclusions, fire, and fractures Hydrostatic Scale Measures specific gravity, works even on opaque stones