18.81 Ct Natural Cat's Eye Tourmaline (Paraíba-Type) | GIA Certified Greenish Blue Tourmaline | Collector Cabochon Gemstone

Product Description

An extraordinary 18.81 carat Natural Cat's Eye Tourmaline, accompanied by a GIA Gemological Report documenting its remarkable chatoyancy phenomenon and attractive greenish blue color. This impressive gemstone belongs to one of the most fascinating and collectible categories within the tourmaline family.

The gemstone displays a distinct and well-defined Cat's Eye effect, a rare optical phenomenon known as chatoyancy, where a bright band of light appears to glide across the surface as the stone is moved under illumination. This mesmerizing effect is highly prized by collectors and is found only in select gemstones possessing the proper internal structure.

Of particular interest, GIA notes that this copper and manganese-bearing tourmaline may be called "Paraíba Tourmaline" in the trade, a designation associated with some of the world's most sought-after and valuable tourmalines. The gemstone exhibits an attractive greenish blue hue combined with a strong cat's eye effect, creating a truly unique collector specimen.

Fashioned as a double cabochon to maximize the visibility of the chatoyancy, this gemstone possesses impressive size, rarity, and visual appeal. At 18.81 carats, it represents a significant collector gemstone suitable for advanced collections, investment portfolios, or exceptional bespoke jewelry creations.

Gemstone Specifications

Gemstone: Natural Cat's Eye Tourmaline

Species: Tourmaline

Variety: Cat's Eye Tourmaline

Weight: 18.81 Carats

Shape: Oval

Measurements: 17.79 × 13.27 × 9.92 mm

Color: Greenish Blue

Transparency: Semi-Transparent to Translucent

Phenomenon: Distinct Chatoyancy (Cat's Eye Effect)

Cutting Style: Double Cabochon

Geographic Origin: Not Requested

Certification: GIA Gemological Report

GIA Report Number: 2546610303

Date: February 11, 2026

Additional GIA Notes

Comments from GIA:

"This copper and manganese bearing tourmaline may be called 'paraíba tourmaline' in the trade."

This designation significantly enhances the gemstone's collector appeal due to the strong market recognition associated with copper-bearing tourmalines.

Why This Gemstone Is Special

✔ Natural Cat's Eye Tourmaline

✔ GIA Certified

✔ Rare Chatoyancy Phenomenon

✔ Copper & Manganese Bearing

✔ Paraíba-Type Trade Classification

✔ Exceptional 18.81 Carat Weight

✔ Attractive Greenish Blue Color

✔ Collector-Grade Gemstone

✔ Rare Optical Effect

✔ Highly Uncommon Combination of Size and Phenomenon