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Natural Amethyst Geode Cathedral - Brazilian Origin

Large vertical amethyst geode cathedral with purple crystals inside a green basalt shell.

Estimated value

$120 - $250

Rarity

Ordinary(3/10)

Category

Gemstones

Era

Post-1990

Origin

🇧🇷 Brazil

Authenticity

Very High(90%)
48

NATURAL AMETHYST GEODE CATHEDRAL - BRAZILIAN ORIGIN: IDENTIFICATION

A vertical amethyst geode 'cathedral' section exhibiting a distinct tri-layer composition: a dark green celadonite-coated basaltic exterior, a thick band of microcrystalline banded agate, and an interior druzy cavity of macrocrystalline quartz. The crystals are characterized by a pyramidal termination habit and a pale-to-medium lavender saturation. The base has been cut flat and appears reinforced with a green-tinted cement or epoxy-basalt mixture to ensure stability for upright display.

Compare with other gemstones in the archive: Natural Diamond - 0.45ct Round Brilliant (GWLAB Certified), 0.50 Carat Round Brilliant Diamond (AIG D2410518829), Natural Tanzanite - 4.51ct Pear Cut (IGE Certified).

SCARCITY

Ordinary40-55%
CommonLegendary

Standard antiques commonly found at estate sales and flea markets. Plentiful supply meets modest demand.

Rarity 3/10. Curiosa currently catalogues 15 gemstones items at rarity 3 or higher.

Typical Characteristics

  • Moderate production runs
  • Common at estate sales
  • Entry-level collectibles

Confidence Factors

  • Geologic structure is consistent with Rio Grande do Sul deposits
  • Agate banding and crystal habit follow natural quartz growth patterns
How does authenticity detection work?

GEMOLOGIST'S TAKE

Gemologist & Mineral Specialist

Gemologist

Identification of species (quartz variety amethyst) and origin (Brazil) is highly reliable based on the specific morphology and preparation style of the specimen.

KEY EVIDENCE

  • 1Hexagonal crystal system evident in visible terminations
  • 2Presence of banded agate 'rim' indicating sequential silica deposition
  • 3Basaltic matrix coated in green-pigmented finish typical of Brazilian production
  • 4Gradation of color from colorless quartz base to amethyst tips

UNCERTAINTIES

  • •Color saturation appears low; potential for color fade if exposed to UV/sunlight over time
  • •Exterior green coating likely masks structural repairs or epoxy reinforcement

WHAT WOULD IMPROVE CERTAINTY

  • →Examine crystals under 10x magnification for 'tiger stripe' twinning or negative crystals
  • →Check the base for a producer's export label or weight in kilograms
  • →View under long-wave UV light to check for dyed resin repairs in the agate rim

CONDITION & GRADE

Grading breakdown

Crystal saturation is in the 'pale' to 'light' range, which is common for larger commercial-grade geodes; higher-grade specimens would show deep purple 'grape' hues.

Condition

Visible mechanical fracture or 'v-cut' on the right-hand side of the agate rim suggests a past impact or stress fracture during the extraction process. Termination points on the interior crystals appear largely intact without significant bruising.

Weight & feel

Estimated at 5.5 to 8.0 kg given its approximate 30 cm height and dense basaltic base.

GEMSTONE VALUATION

$120 - $250

Updated: May 10, 2026

Who buys this

Interior decorators and mineral collectors looking for 'statement' bookshelf or tabletop pieces.

What increases value

  • •Depth and saturation of the purple color
  • •Completeness of the crystal terminations (no bruising)
  • •Height and presence as a vertical display piece

What lowers value

  • •Heat or sunlight exposure causing color loss
  • •Structural cracks in the agate rim
  • •Excessive artificial cement on the base increasing weight without adding value

What makes top-tier examples

  • •Deep 'Siberian' purple color saturation
  • •Presence of 'flower' formations or large calcite inclusions
  • •Thin matrix wall relative to crystal volume

Grade & condition

Determined by color saturation (A to AAAA), crystal size, and matrix stability.

Rarity & demand

OrdinaryHigh demandSells quickly
Browse similar gemstones objects

For informational purposes only, not a formal appraisal.

FROM THE CABINET OF

TH

The Vault
Wonderseeker•4 items

COMMENTS (1)

The Collector
The Collector5 months ago

Did you find this amethyst yourself?

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