Brazilian peridot is an obsolete and gemmologically inaccurate trade name historically applied to yellowish-green chrysoberyl originating from Brazil — a material entirely unrelated to true peridot. The term is a misnomer of the first order: chrysoberyl (beryllium aluminium oxide, BeAl₂O₄) and peridot (magnesium iron silicate, (Mg,Fe)₂SiO₄) belong to wholly different mineral species, differ substantially in hardness, refractive index, specific gravity, and crystal system, and share only a superficial colour resemblance in certain stones. Modern gemmological standards, including those of the Gemological Institute of America and the International Coloured Gemstone Association, prohibit the use of such misnomers in professional trade contexts. The term survives today only in antique inventories, estate jewellery documentation, and historical literature, where it must be recognised and correctly interpreted rather than perpetuated.

Origins of the Misnomer

The name arose during the late nineteenth and early twentieth centuries, a period when colour alone frequently governed the popular and even commercial naming of gemstones. Systematic gemmological testing — refractive index measurement, specific gravity determination, spectroscopic analysis — was not yet routine practice in the trade, and stones of similar hue were routinely grouped under a single convenient label regardless of their mineralogical identity. Yellowish-green chrysoberyl from the gem-bearing pegmatites and alluvial deposits of Minas Gerais, Brazil, can display a colour that, to the untrained eye, resembles the characteristic olive-to-bottle-green of peridot. This visual similarity, combined with Brazil's prominence as a gemstone-producing nation, led dealers to apply the familiar name peridot with a geographical qualifier, producing the compound misnomer.

The practice was not unique to this pairing. The same era generated a catalogue of comparable misnomers — "Ceylon peridot" for yellowish-green tourmaline, "Indian emerald" for green-dyed quartz, "Bohemian ruby" for pyrope garnet — all of which have since been formally deprecated. "Brazilian peridot" belongs squarely in this company.

The Actual Material: Chrysoberyl

The stone correctly described by the historical term is chrysoberyl, a beryllium aluminate crystallising in the orthorhombic system. Its principal gemmological properties stand in marked contrast to those of peridot:

• Hardness: 8.5 on the Mohs scale (chrysoberyl) versus 6.5–7 (peridot) — a difference of practical significance for durability in jewellery.
• Refractive index: 1.746–1.755 (chrysoberyl, biaxial positive) versus 1.654–1.690 (peridot, biaxial positive) — well separated and readily distinguished with a refractometer.
• Specific gravity: approximately 3.71–3.75 (chrysoberyl) versus 3.27–3.37 (peridot).
• Crystal system: orthorhombic in both species, but with entirely different unit-cell parameters and habit.
• Characteristic absorption: chrysoberyl shows iron-related absorptions in the blue; peridot displays a distinctive trio of absorption bands in the blue-green (at approximately 493, 473, and 453 nm) attributable to ferrous iron.

Yellowish-green chrysoberyl from Minas Gerais ranges from a pale, almost citrine-like yellow-green to a richer, more saturated olive tone. The finest material is transparent and eye-clean, with a vitreous to slightly resinous lustre. Brazil has been a significant source of chrysoberyl for well over a century, with the states of Minas Gerais, Bahia, and Espírito Santo all yielding gem-quality material from granitic pegmatites and associated alluvial gravels.

True Peridot: A Distinct Species

For the sake of clarity, true peridot — the gem variety of the mineral olivine — is a magnesium iron silicate whose colour is produced by ferrous iron (Fe²⁺) in the crystal structure, yielding the characteristic warm, slightly yellowish green that has been prized since antiquity. Its principal historic sources include the island of Zabargad (St John's Island) in the Red Sea, the San Carlos Apache Reservation in Arizona, Myanmar (Burma), Pakistan's Kohistan district, and China. Brazil is not among the historically significant sources of genuine peridot, which makes the geographical qualifier in "Brazilian peridot" doubly misleading: the stone is neither peridot nor a material for which Brazil is a recognised peridot producer.

Gemmological Identification

Distinguishing chrysoberyl from peridot presents no meaningful challenge to a trained gemmologist equipped with standard instruments. The refractometer reading alone is conclusive: chrysoberyl's refractive indices fall well above peridot's, and the birefringence values differ sufficiently to preclude confusion. Specific gravity testing, Chelsea filter examination, and spectroscopic analysis all provide corroborating evidence. In the absence of instruments, the substantially greater hardness of chrysoberyl (it will not be scratched by quartz; peridot can be) offers a preliminary field indicator, though destructive testing of finished stones is rarely appropriate.

For estate pieces or antique jewellery where documentation uses the term "Brazilian peridot," a gemmological laboratory report identifying the material as chrysoberyl is the appropriate resolution before any resale or insurance valuation is undertaken.

In the Trade and in Historical Literature

The International Coloured Gemstone Association and the GIA both maintain lists of deprecated trade names, and "Brazilian peridot" appears among those that should not be used in modern commercial descriptions, grading reports, or auction catalogues. Reputable auction houses, when handling antique pieces described in period documentation with this term, will typically note the historical name in quotation marks while providing the correct mineralogical identification in the body of the catalogue entry.

The term retains legitimate use in one narrow context: the history of gemmology and the history of the gem trade. Scholars examining early twentieth-century trade catalogues, jewellery inventories, or correspondence will encounter it regularly, and understanding its referent — yellowish-green Brazilian chrysoberyl — is essential to accurate interpretation of those documents. In this sense, "Brazilian peridot" is a piece of gemmological history: a record of how colour-based nomenclature, in the absence of systematic mineralogical testing, generated a lexicon of misnomers that the discipline has spent the better part of a century correcting.

Further Reading

• GIA Gem Encyclopedia: Chrysoberyl
• GIA Gem Encyclopedia: Peridot
• ICA Gem Encyclopedia: Chrysoberyl