Visual Clues for Treated Rubies

Identifying whether a ruby is natural, oiled, heat-treated, or fracture-filled requires close examination. Key visual clues can help distinguish between untreated and treated rubies, allowing buyers to make informed decisions. Understanding these differences ensures transparency in the gemstone market and prevents misrepresentation.

1. Natural (Untreated) Ruby – Key Visual Clues

A natural, untreated ruby retains its original formation characteristics, often displaying inclusions that are considered natural fingerprints of the gemstone.

What to Look For:

• Silk Inclusions: Fine, needle-like rutile inclusions are often visible under magnification.
• Zoning in Color: Natural rubies may have uneven color distribution, creating a slightly patchy or banded appearance.
• Minor Internal Fractures: Some natural fractures are expected but should not overly impact clarity.
• No Artificial Shine in Fractures: Untreated rubies have a consistent, natural luster.

2. Oiled Ruby – Key Visual Clues

Oiling is a temporary treatment used to enhance clarity by filling surface-reaching fractures with a clear oil or resin.

What to Look For:

• Glossy or Greasy Appearance in Fractures: Under magnification, oil-filled areas may appear slightly shinier than the surrounding material.
• Clarity Changes Over Time: If the ruby appears duller after cleaning, it may have been oiled.
• Bubbles or Residue in Cracks: In some cases, traces of oil or filler may be visible inside fractures.

3. Heat-Treated Ruby – Key Visual Clues

Heat treatment is the most common enhancement used to improve ruby color and clarity by dissolving inclusions.

What to Look For:

• Partially Dissolved Silk Inclusions: Under magnification, rutile silk may appear blurred or broken due to heat exposure.
• More Even Color Distribution: Heated rubies tend to have improved, more uniform color compared to untreated stones.
• Clean Internal Structure: Some naturally included rubies become clearer after heat treatment, but inclusions may still be present.

4. Lead-Glass-Filled Ruby (Fracture-Filled) – Key Visual Clues

This treatment uses lead glass to fill fractures, making low-quality rubies appear clearer but reducing durability.

What to Look For:

• Flash Effect: Under magnification, fractures filled with lead glass may show flashes of blue, orange, or purplish light.
• Bubbles Inside the Stone: Unlike natural inclusions, trapped air bubbles are a clear sign of glass filling.
• Excessive Transparency in Heavily Included Rubies: If a ruby appears unusually clear despite having many fractures, it may be lead-glass-filled.
• Fragile Surface: Fracture-filled rubies can be damaged by mild acids or even household cleaners.

5. Diffusion-Treated Ruby – Key Visual Clues

Diffusion treatment alters a ruby’s color by introducing elements like beryllium under high heat.

What to Look For:

• Superficial Coloration: The color may appear concentrated on the surface rather than penetrating deep into the gemstone.
• Visible Color Bleeding: Under magnification, color may be uneven or fade near the edges.
• White or Pale Interior: When cut open, diffusion-treated rubies may have a much lighter core than their surface.

6. Flux-Healed Ruby – Key Visual Clues

Flux healing is a variation of heat treatment where flux material is added to heal fractures, filling them with synthetic ruby-like substances.

What to Look For:

• Golden or Whitish Residue in Fractures: Flux material often leaves traces that can be seen under magnification.
• Inclusions with a Melted Look: Flux-filled fractures may have a smooth, glassy texture rather than a rough, natural appearance.
• Lesser Value Than Untreated or Purely Heat-Treated Rubies: While durable, flux-healed rubies are priced lower than standard heat-treated stones.

How to Verify a Ruby’s Treatment

• Use a Jeweler’s Loupe or Microscope: Magnification helps identify inclusions, bubbles, or color inconsistencies.
• Perform a Light Test: A well-lit environment can reveal flash effects in lead-glass-filled rubies.
• Request a Gem Lab Certification: Reports from GIA, AGL, or SSEF confirm whether a ruby has undergone treatments.
• Ask About the Source: Rubies from reputable sellers often come with full disclosure about their treatments.

Conclusion

Recognizing key visual clues in rubies helps buyers differentiate between natural, oiled, heat-treated, and fracture-filled gemstones. While some treatments, like heat treatment, are widely accepted, others, like lead-glass filling, significantly affect value and durability. Always verify ruby authenticity through professional certification to ensure transparency and an informed purchase.

For more details, explore Is Oiling Permanent? to learn how long this ruby enhancement lasts and what it means for your gemstone.