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Where is Faceted Gemstone found?

Unknown Gemstone (possibly Sapphire or Spinel based on color and cut)

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Faceted Gemstone occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.

Where to find Faceted Gemstone

Sri Lanka

Renowned for both sapphire and spinel, particularly from alluvial deposits in the Ratnapura district.

Myanmar (Burma)

Famous for high-quality rubies and sapphires, and also for fine red and blue spinels, especially from the Mogok Stone Tract.

Madagascar

A significant source of sapphires, particularly from the Ilakaka and Andranondambo regions. Spinel is also found.

Thailand/Cambodia

Historically important sources of blue sapphires, often found in basaltic terrains.

Australia

Known for dark blue sapphires, particularly from Queensland and New South Wales.

United States (Montana)

Produces various colors of sapphire, including blue, from Yogo Gulch and other localities.

Vietnam

Emerging source of both sapphire and spinel.

Collecting tips

  1. Professional Gemological Testing. The most reliable method for distinguishing between sapphire and spinel (or other blue gemstones) is through professional gemological testing, which includes refractive index (RI), specific gravity (SG), spectroscopy, and polariscopy. Sapphire is doubly refractive, while spinel is singly refractive.
  2. Hardness Test (Destructive). While not recommended for a faceted gemstone, sapphire (Mohs 9) is harder than spinel (Mohs 8). This test would damage the stone.
  3. Inclusions. Examining internal inclusions under magnification can provide clues. Sapphire often exhibits rutile needles ('silk'), growth zoning, and fingerprints. Spinel may show octahedral crystals or stress fractures.
  4. Pleochroism. Sapphire is pleochroic (shows different colors when viewed from different angles), while spinel is not. This can be observed with a dichroscope.

Quick Check

Color:
Blue (various shades)
Luster:
Vitreous to adamantine
Streak:
White (for both sapphire and spinel)

Explore Faceted Gemstone

Overview

Full guide to Faceted Gemstone

Identification

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