Large Raw Black Tourmaline Crystal | Mineral Specimen for Sale

1.  Transparency Types

These terms describe how much light passes through a gem.

• Transparent: Light passes through the stone clearly and undistorted, allowing objects to be seen clearly through it. Examples: Fine diamond, sapphire, and emerald.

• Semi-Transparent: Light passes through the stone, but it is diffused. Objects on the other side are seen as blurred shapes. Examples: Some sapphires, garnets, and topaz.

• Opaque: No light passes through the stone. It is impenetrable to light. Examples: Lapis lazuli, turquoise, and malachite.

2. Common Clarity Grades (Based on the GIA Diamond Scale)

• Included (I1, I2, I3): Obvious inclusions that are visible to the naked eye. They can affect transparency, durability, and brilliance.

• Slightly Included (SI1, SI2): Inclusions are noticeable with medium effort using a 10x loupe and may be visible to the naked eye. SI1 inclusions are often harder to see without a loupe than SI2.

• Very Slightly Included (VS1, VS2): Minor inclusions that are difficult to see with a 10x loupe. They are not visible to the naked eye. This is considered excellent clarity.

• Very, Very Slightly Included (VVS1, VVS2): Minute inclusions that are extremely difficult to see under 10x magnification. They are invisible to the naked eye. This is a high grade of clarity.

3. Descriptive Clarity Terms

These terms describe how a stone appears to the viewer, not under magnification.

• Eye Clean: A practical term meaning that no inclusions are visible to the naked eye (without magnification). A stone can be graded SI or VS and still be "eye clean," which is often an excellent value.

• Loupe Clean: A term meaning no inclusions are visible under 10x magnification. This is very rare and indicates a stone of exceptional clarity. It is similar to a Flawless or Internally Flawless grade.

1. No Treatment (None)

The gemstone is in its natural state as found in the earth. It has not been subjected to any heat, radiation, or filling processes.

2. Heated (Thermal Treatment) - "Standard Heated"

The application of heat to improve color and/or clarity. This is a traditional, accepted practice for stones like sapphire, ruby, and tanzanite.

3. Beryllium Diffused / "Beryllium Heated"

A more advanced heating process where gems are heated with elements like beryllium to deeply infuse color into the stone. This can create vibrant oranges, pinks, and yellows, often in sapphires.

4. Minor Oil / Clarity Enhancement

 A common practice for emeralds, where a colorless oil or resin is used to fill surface-reaching fractures, improving clarity and stability.

• Why it matters:

  • Minor Oil/Faint: Indicates a small amount of residue. This is expected for most emeralds and requires only standard care.

  • Moderate to Significant Oil/Resin: The treatment is less stable. The filler can dry out, discolor, or be damaged by heat, ultrasound cleaners, or harsh chemicals. These stones require special care and may need re-treatment over time.