Garnet is not one stone.

Member 01 · Mg–Al garnet

Pyrope

Mg₃Al₂(SiO₄)₃

The magnesium–aluminium end member. It turns up in several deep-source and high-pressure settings, which is exactly why the name on its own tells you nothing about where a stone came from.

Structure

X site: Mg²⁺
Y site: Al³⁺

Colour range

Commonly purple-red, pinkish red, red-orange or deep red; some material appears nearly black, and unusual colour-change examples are documented.

Formation context

Documented in peridotites, kimberlites and eclogites, and also in serpentinites, some schists, anorthositic rocks and detrital deposits.

Nested names

Rhodolite names purplish red Pyrope–Almandine garnet. Chrome Pyrope needs chromium evidence. Neither is a separate species — and these six are only the familiar ones. The IMA garnet supergroup holds 32 approved species.

What the eye can record

Hue, tone, transparency, inclusions and lighting. None alone identifies Pyrope or demonstrates a source environment.

What testing must establish

Overlapping solid solutions may require spectroscopy and chemical analysis. Origin and treatment require separate evidence.

Sources: IMA nomenclature · Handbook of Mineralogy · GIA laboratory note

Member 02 · Fe–Al garnet · First pathway

Almandine

Fe²⁺₃Al₂(SiO₄)₃

The iron–aluminium end member, and the one you meet most often in metamorphic rock. The formation walk-through starts here because this is the BE. stone. That walk-through is a general model, not this bead’s history.

Structure

X site: Fe²⁺
Y site: Al³⁺

Colour range

Commonly deep red, brownish red or red-violet; some specimens appear black, and colour zoning can occur.

Formation context

Especially common in regionally metamorphosed pelitic rocks; also documented in hornfels, granites, eclogites, sediments and detrital deposits.

Nested names

Rhodolite names purplish red Pyrope–Almandine material; the colour is part of the definition, not just the composition. Fe²⁺–Mn²⁺ substitution also produces Almandine–Spessartine mixtures.

BE. record level

The current lot is recorded at sourcing level as Almandine. That is documentation, not an independent laboratory determination.

Testing boundary

Optical properties and spectroscopy can support classification; mixed compositions may require chemical analysis.

Sources: IMA nomenclature · Handbook of Mineralogy · Manzotti et al. 2025

Member 03 · Mn–Al garnet

Spessartine

Mn²⁺₃Al₂(SiO₄)₃

The manganese–aluminium end member. Known for orange stones, though orange is not what makes a stone spessartine.

Structure

X site: Mn²⁺
Y site: Al³⁺

Colour range

Orange, reddish orange, red-brown and other tones can occur depending on composition and trace constituents.

Formation context

Documented in granitic pegmatites and Mn-rich metamorphic or metasomatic environments.

Nested names

“Mandarin Garnet” is a trade label. It is not a mineral species and does not, alone, establish origin.

What the eye can record

Orange body colour, transparency, inclusions and how colour responds to stated illumination.

What testing must establish

Species or composition, trace-element causes and any origin or treatment statement.

Sources: IMA nomenclature · Handbook of Mineralogy · GIA gem-garnet classification

Member 04 · Ca–Al garnet

Grossular

Ca₃Al₂(SiO₄)₃

The calcium–aluminium end member. Most people know the green variety. The species itself runs from colourless through yellow and orange to red.

Structure

X site: Ca²⁺
Y site: Al³⁺

Colour range

Colourless, yellow, orange, brown, pink, red and green material is documented.

Formation context

Common in calc-silicate metamorphic rocks, skarns and calcium-rich metasomatic settings.

Nested names

Tsavorite is a green Grossular variety; Hessonite names yellow-orange to reddish orange Grossular material, sold in the trade as cinnamon stone.

What the eye can record

Visible colour and optical character. A green appearance can justify the word “green”, not automatically “Tsavorite”.

What testing must establish

Composition, variety criteria, cause of colour and any geographic-origin claim.

Sources: IMA nomenclature · Handbook of Mineralogy · GIA classification

Member 05 · Ca–Fe³⁺ garnet

Andradite

Ca₃Fe³⁺₂(SiO₄)₃

The calcium–ferric-iron end member. Demantoid is its green variety, which is not the same as saying andradite means green.

Structure

X site: Ca²⁺
Y site: Fe³⁺

Colour range

Green, yellow-green, yellow, brown and black appearances occur among Andradite varieties.

Formation context

Documented in skarns and other contact-metasomatic settings, in serpentinite-associated environments, and in alkaline igneous rocks, where the titanium-rich black Melanite typically forms.

Nested names

Demantoid, Topazolite and Melanite are variety names within Andradite.

Optical note

Demantoid has high measured dispersion, but visible fire also depends on body colour, clarity, cut and lighting.

What testing must establish

Composition, variety assignment and any locality or treatment claim.

Sources: IMA nomenclature · Handbook of Mineralogy · GIA Topazolite note

Member 06 · Ca–Cr garnet

Uvarovite

Ca₃Cr³⁺₂(SiO₄)₃

The calcium–chromium end member, usually found as small bright green crystals crusted on rock. That habit is why it reaches jewellery as drusy rather than as cut stones.

Structure

X site: Ca²⁺
Y site: Cr³⁺

Forms a continuous series with Grossular.

Colour range

Characteristically green, with tone and saturation varying among specimens and mixed compositions.

Formation context

Commonly associated with chromite-bearing ultramafic rocks and serpentinite-related settings.

Jewellery context

Usually small crystals preserved as drusy or cluster-set material; rare larger or faceted Uvarovite-rich material is documented.

What the eye can record

Crystal size, cluster habit, surface coverage and visible green colour.

What testing must establish

Composition, whether material is Uvarovite-dominant and any specific geological source.

Sources: IMA nomenclature · Handbook of Mineralogy · Gemdat cut-stone records