Andalusite
Brazil, Sri Lanka
Andalusite is an aluminum silicate mineral notable for strong pleochroism, showing different colors—typically green, brown, red and yellow—when viewed from different directions. With Mohs hardness around 7–7.5 and good stability, it can be used in most jewelry settings.
Price History
Value Drivers
Fine andalusite is usually seen in smaller sizes; stones above 3–4 carats with strong pleochroism and good clarity are less common and collectable. Carat weight thus adds value when accompanied by strong color effects.
Color and pleochroism are the primary value drivers. Stones showing an attractive mix of green, golden and reddish tones in a single view are most prized. Flat brown or muddy colors without play significantly reduce appeal.
Buyers prefer eye-clean stones to fully appreciate the pleochroic colors. Feathers or inclusions that break the surface or disrupt transparency lower value, although minor internal features are tolerated in smaller stones.
Cutting is crucial for andalusite: orientation determines which pleochroic colors dominate. Skilled cutters aim for face-up mixes of complementary hues, often using elongated or rectangular shapes to maximize color play.
Market Dynamics
Andalusite occurs in metamorphic rocks in several countries, including Brazil, Sri Lanka and Spain, but only a small portion is of gem quality. Most production is modest-scale and fed into the colored-stone trade sporadically.
Demand is niche, coming mainly from collectors, connoisseurs and designers seeking unusual color effects. It does not have strong mainstream branding, but its uniqueness supports steady, if limited, demand.
Recent Trends: niche but stable collector interest, with fine, well-documented stones achieving strong prices through specialist dealers and auctions.
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Insights
Andalusite is part of the same chemical family as sillimanite and kyanite, with each polymorph forming under different pressure and temperature conditions.
Stones with a clear cross-shaped inclusion pattern are known as chiastolite, a variety of andalusite prized more as a collector and ornamental stone than as a faceted gem.
Brazil is a leading supplier of facetable andalusite, providing much of the material seen in modern jewelry.
Because of the pronounced pleochroism, andalusite can appear to shift color as the stone moves, giving it a dynamic, 'earthy fireworks' appeal in well-designed pieces.
Andalusite is generally not treated, so buyers value it as a largely 'natural' gem compared to more heavily treated species.
Despite its unique optical properties, andalusite remains under-recognized with the general public, leaving room for storytelling-driven value creation in designer lines.
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