Grandidierite

Grandidierite From Madagascar .82CT

Grandidierite is an extremely rare borosilicate mineral, famously prized for its striking bluish-green and greenish-blue hues. First discovered in southern Madagascar in 1902, it is one of the world's top ten most expensive and sought-after gemstones. 

Key Characteristics of Grandidierite

• Origin & Rarity: While trace deposits exist globally, Madagascar and Sri Lanka are the only places that produce gem-quality, facetable rough. Most of the gem-grade supply comes from the Anosy region (near Tolanaro and Tranomaro). 
• Hardness: Rates at a durable 7.5 on the Mohs scale, making it suitable for certain jewelry pieces, though it possesses a perfect cleavage that makes cutting difficult. 
• Pleochroism: The stone features trichroic properties, meaning it shows three different colors depending on the angle of observation: dark blue-green, dark green, and colorless (or light yellow). 
• Inclusions: Natural grandidierite is rarely eye-clean; it is heavily characterized by fine, pin-shaped inclusions and channels, which are a hallmark of the untreated, natural stone. 

Sourcing and Availability

Because it is a single-origin stone heavily localized to Madagascar, finding this gem can be quite challenging for collectors. Smaller, translucent or translucent-to-opaque cabochons can be found on collector and artisan platforms, while facet-grade, eye-clean material above 1 carat commands a premium.