Madagascar alexandrite is the colour-change variety of chrysoberyl found within the alluvial gem fields of southern Madagascar, principally around Ilakaka, Sakaraha and the Tsarafara region. Although Madagascar is far better known for sapphire, parcels of alexandrite have appeared steadily in the Ilakaka deposits since the late 1990s and have since become a recognised commercial source alongside Brazil, Sri Lanka, Tanzania and the Russian Urals.

Material character

The Madagascan stones tend to show a daylight colour ranging from greyish green to bluish green, shifting to purplish red or brownish red under incandescent light. The change is usually moderate to strong rather than the textbook "emerald by day, ruby by night" of the historic Ural material, although exceptional examples do appear. Most rough is small, with clean stones above two carats considered noteworthy and stones above five carats genuinely scarce.

Inclusion scenes commonly show fine silk, two-phase inclusions and healed fingerprints, consistent with the metamorphic-pegmatite origin attributed to the host terrain. Refractive index, specific gravity and absorption spectra fall within the standard chrysoberyl range, with chromium responsible for the colour change and minor iron tempering the daylight hue.

Trade and grading

Stones are typically extracted by artisanal miners working the gravel terraces and washed at small jig plants before being sold through Ilakaka and Antananarivo. The bulk of cuttable rough moves to Bangkok and Chanthaburi for faceting. Reports from GIA and from Gems & Gemology field expeditions have confirmed the deposit's geological context and noted that origin determination from inclusions alone is rarely conclusive: laboratories generally rely on trace-element chemistry to separate Madagascan material from East African and Brazilian alexandrite.

For collectors, Madagascan alexandrite offers the most accessible route into a meaningful colour-change chrysoberyl below the prices commanded by fine Russian or Sri Lankan goods, provided the change is genuine and not merely a shift between two muddy hues.