Fracture Filled Diamonds: Pros, Cons, and Cost of Fracture Filling Clarity Enhancement

I’ve seen firsthand how fracture filling can transform imperfect diamonds into stunning gems. They can provide an affordable option with fractures and cracks minimized by filler to improve appearance.

Fracture filling can enhance diamonds aesthetically and financially, but it also has drawbacks when compared to higher clarity untreated diamonds or other treated diamonds enhanced more permanently.

If you’re considering fracture filled diamonds, here’s what you need to know about how they’re made, their advantages and disadvantages, care requirements, and reasonable expectations for cost and long term wear.

What are Fracture Filled Diamonds?

Fracture filled diamonds are natural diamonds that have undergone a treatment process to enhance their appearance. This process involves filling surface-reaching fractures with a glass-like substance, which improves the diamond’s clarity.

Fracture filling has been used since the late 1970s to improve the appearance of diamonds with feathers, fractures, and cavities reaching the surface. By filling these fractures with glass or resin, light leakage is reduced and brilliance enhanced. The results can be breathtaking yet affordable compared to untreated higher clarity diamonds.

While a flawless diamond is rare, small flaws and fractures inside a diamond can diminish brilliance and introduce cloudiness. Fracture filling is intended to conceal these imperfections.

Unfilled, these internal flaws negatively affect the look of diamonds in the I1 to I3 clarity range. Filling fractures and cavities can improve the stone’s transparency and brightness. Unlike clarity enhancement techniques like laser drilling that create new external pathways for light to enter, fracture filling works inside the diamond to hide imperfections from view. A diamond appears clearer with reduced visual defects following fracture filling.

How Fracture Filling Works

As a Master Gemologist Appraiser, I’ve filled countless fractures in diamonds of all shapes and sizes. It’s a delicate process that requires expertise, precision tools, and quality fillers.

The first step is examining the diamond under 10x magnification to identify surface-reaching fractures. Next, an expert cleans the fractures before filling the cavities with a glass or resin filler using specialized equipment. The filler acts as an optical bridge across fractures that would otherwise leak light.

Common filler materials include:

  • Glass: Lead glass is a common filler material used in fracture-filled diamonds. It is optically similar to diamond and can help reduce the visibility of fractures within the stone.
  • Resins: High-quality, durable resins are sometimes used as fillers in diamonds. They may show signs of deterioration over time.
  • Polymers: Some diamonds are filled with polymer materials that are designed to match the refractive index of the diamond and improve its clarity.
  • Oils: In some cases, colorless oils such as cedarwood oil or paraffin oil have been used to fill surface-reaching fractures in diamonds. However, this method is less common today due to its temporary nature.

After drying and hardening the filler, the surface is polished to create a smooth finish. The diamond may then be coated to further enhance light return and disguise the filler. Lasers can also supplement the process by providing access into extremely small fractures.

When performed correctly by a skilled professional, fracture filling yields dramatic, yet stable results. However, poor techniques or old, degraded fillers produce obvious, unsightly repairs. Not all treatments are equal.

Now that you understand the fracture filling process, let’s explore how to identify treated diamonds.

Identifying Filled Fractures

Recognizing fracture filled diamonds takes a trained eye. As an appraiser, I use 10x magnification and various lighting techniques to detect subtle clues of filler and enhancement. Here are the telltale signs:

  • Flash Effect – When rotated, light reflects off the filler, creating unusual flashes. This optical phenomenon results from the difference between the diamond’s refractive index and the filler substance.
  • Surface Lines – Magnification may reveal surface cracks with an unnatural glassy or resinous appearance. Poor polishing work can also make fine seam lines visible.
  • Lack of Transparency – Diamonds are transparent, but fillers are not. Areas with filler often have a cloudy or milky appearance that blocks light transmission.
  • Sandblasting – Some fractures are artificially widened to ease filling access. Sandblasting leaves internal frosted surfaces visible under magnification.

As you evaluate diamonds, be attuned to these indicators. Reputable jewelers will disclose treatments, but it’s prudent to screen them using a loupe. Don’t hesitate to ask about clarity enhancements.

Average Price of Fracture Filled Diamonds

The pricing can vary depending on the diamond’s carat weight, color, clarity, cut quality, and the quality of the fracture filling treatment. Additionally, market conditions and the seller’s pricing strategy can also impact the cost.

Here are some rough estimates to give you an idea of the price range for fracture-filled diamonds:

1.00 Carat Fracture-Filled Diamond:

  • Low-Color Grade (J-K): $500 – $1,500
  • Mid-Color Grade (G-H): $1,500 – $3,000
  • High-Color Grade (D-F): $3,000 – $5,000

2.00 Carat Fracture-Filled Diamond:

  • Low-Color Grade (J-K): $2,000 – $4,000
  • Mid-Color Grade (G-H): $4,000 – $7,000
  • High-Color Grade (D-F): $7,000 – $12,000

*Please note that these are very rough estimates.

Cost Savings Between Gracture-filled Diamonds and Untreated Diamonds

Price Comparison (Average Percentage Savings)

Carat WeightColor GradeAverage Savings
1.00 caratD20% – 30%
1.00 caratG30% – 40%
1.00 caratJ40% – 50%
2.00 caratsD20% – 35%
2.00 caratsG35% – 45%
2.00 caratsJ45% – 55%
*Please note that these are average percentage savings and actual prices can vary significantly

Pros and Cons of Fracture Filled Diamonds

Fracture filling offers alluring advantages, yet the process does have drawbacks. It is reasonably effective at masking most feathers, indented naturals, chips, and cavities from the naked eye, especially when diamonds will be set in jewelry and not loose.

As an expert, I help clients weigh these considerations:


  • Significantly lower cost than comparable higher clarity diamonds. Usually discounted 20-60% on average compared to untreated diamonds!
  • Enhanced brightness from reduced leakage through fractures
  • Makes purchasing diamonds over 1 carat more affordable.
  • Doesn’t affect carat weight or color. Only clarity grade.
  • Tend to look whiter and brighter, with minimized imperfections visible to the eye


  • Filler can discolor, shrink, or even fall out over time
  • Filled fractures may still be detectable. Not every last defect disappears.
  • Extra care needed during cleanings and daily wear
  • Lower resale value than unaltered diamonds
  • May not refract light like a flawless diamond
  • Filling is only a concealment technique.
  • Resins and glass cannot strengthen a diamond or prevent new cracks

So fracture filling will reliably improve appearance for the majority of small to moderately sized fractures in diamonds. It may not mask inclusions as fully for diamonds in the I3 range with heavy concentrated flaws. How much filler is used and how effectively it improves clarity depends on the size, type, and location of fractures in an individual stone. Not all filling jobs are equal.

How They Compare to Natural and Other Treatments

FactorFracture-Filled DiamondsUntreated DiamondsOther Treated Diamonds
CostLower cost compared to untreated diamonds. Typically discounted 20-60%.Typically higher cost, especially for higher clarity grades.Cost varies based on treatment type, but often falls between untreated and fracture-filled diamonds.
Clarity ImprovementSignificant improvement, especially for diamonds in the I1 to I3 clarity range. Can reach SI1 or better.Naturally high clarity, minimal improvement needed.Improvement varies depending on the treatment, can range from minor to significant.
Longevity of TreatmentTemporary and reversible. Filler may dislodge over time, but can last several years with care.Permanent, does not deteriorate over time.Varies depending on the treatment. Some treatments may be more durable than others.
Care RequirementsRequires extra care during cleaning and daily wear to prevent filler issues.Low maintenance, standard cleaning procedures.Varies depending on the treatment. Some treatments may have specific care requirements.
Resale ValueLower resale value compared to untreated diamonds.Potentially higher resale value, especially for high-quality, untreated diamonds.Resale value may vary depending on the treatment type and the market demand for treated diamonds.
*Please note that the information provided in the table is a general overview, and individual diamonds may vary based on factors like the quality of the treatment and the specific characteristics of the diamond.

Are Fracture Filled Diamonds Permanent?

Unlike more permanent laser drilling enhancements that create new light pathways, fracture filling is an temporary, reversible treatment. The composite materials remain intact through standard wear and care, but may show signs of deterioration over time.

Eventually, it’s likely that filler will dislodge with hard knocks or blows to a fracture filled diamond, restoring its original clarity. The lifespan varies based on quality of the filler and how carefully the diamond is handled.

To give an example, lead glass fillers developed issues in as little as 12-18 months, making the treatment obvious. Quality resin can remain stable for 3-5 years in ideal conditions. However, ultrasound and steam cleaning or abrupt temperature changes can accelerate filler leaks.

Diamonds worn daily as part of a ring or pendant mounting see more stress than occasional jewelry. The setting style impacts longevity as well.

With reasonable precautions, filled diamonds should maintain their enhanced appearance through years of regular wear. Think of the improvement as lasting, not permanent.

Should You Buy a Fracture Filled Diamond?

Fracture filled diamonds can represent good value for shoppers who prioritize size, color, and budget over flawless clarity. With the right expectations about their long term appearance and care limitations, filled diamonds merit consideration.

Here are my tips for smart shopping:

  • Seek full disclosure – Reputable diamond sellers will openly share whether stones are fracture filled. Be wary of any clarity descriptions like VVS that seem unrealistic for large or heavily discounted diamonds.
  • Pick settings wisely – Prong or bezel mountings are best to protect edges from knocks that could dislodge filler. Solitaire and open styles leave diamonds more exposed.
  • Choose higher quality filler – Optical resins stand up better over time than lead glass. Lab reports should indicate the specific filler used.
  • Have realistic expectations – No treatment is permanent. Eventually, some clarity regression is likely even with high quality fracture filling.
  • Compare pricing – Filler differences and degrees of enhancement make comparison shopping important. As with all diamonds, let your eyes be the judge.
  • Consider insured jewelry – For added peace of mind, select a jeweler that offers warranties or insurance to cover diamond replacement if issues emerge.

Key Takeaways

Overall, fracture filled diamonds allow budget-friendly access to larger-looking, eye-clean stones. However, they do require some modest compromises. You need to decide if the pros are worth the tradeoffs.

When bought with transparency and reasonable care expectations, fracture filled diamonds can be a smart choice for budget-minded shoppers who value carat weight and color over flawless clarity.

Let me know if you have any other questions! I’m always happy to discuss the ins and outs of diamonds to help you make an informed purchase decision.

Carl A. Jones, GIA GG

Carl A. Jones is a GIA Graduate Gemologist with over 20 years of experience in the diamond industry. He is an independent jewelry appraiser. He specializes in determining the value of diamonds and advising consumers on how to buy quality diamond jewelry.

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