Lubrication in Gemstones

Lubrication is a common gemstone enhancement process that involves impregnating a gemstone with a foreign substance, typically a polymer or oil, to fill surface-reaching fractures and improve clarity and appearance. This treatment is widely used in the industry, particularly for softer gemstones or those with natural inclusions that affect their beauty.

Definition

Gemstone lubrication, also known as fracture filling or impregnation, is a process where tiny surface-reaching fissures or cavities within a gemstone are filled with a transparent material. This material, often a glass-like polymer, resin, or oil, serves to make these imperfections less visible to the naked eye and microscope, thereby enhancing the gem's overall clarity and brilliance. The goal is to improve the aesthetic appeal of the stone.

Key Features

• Improved Clarity: The primary goal of lubrication is to reduce the visibility of internal fractures and inclusions, making the stone appear cleaner.
• Enhanced Brilliance: By filling in cracks, lubrication can reduce light leakage, leading to a more vibrant and brilliant appearance.
• Temporary or Permanent: Depending on the filling material used (e.g., oil vs. polymer), the enhancement can be temporary or have a longer lifespan.
• Surface Treatment: Lubrication primarily addresses surface-reaching features, not internal characteristics deep within the stone.
• Disclosure is Key: Reputable dealers must disclose gemstone lubrication to buyers, as it affects the gem's durability and value.

How It's Made

The lubrication process typically involves several steps:

1. Cleaning: The gemstone is thoroughly cleaned to remove any surface dirt or oils.
2. Impregnation: The cleaned stone is placed in a bath containing the filling material. This can be done under heat and pressure, or using vacuum methods, to ensure the material penetrates deep into the surface-reaching fractures.
3. Curing/Setting: For polymer-based fillers, a curing process (often involving UV light or heat) is employed to harden the material. For oils, the material simply saturates the fissures.
4. Polishing: The stone is then polished to remove any excess filler material from the surface, leaving a smooth, clean finish.

The choice of filling material is crucial. Oils, while effective initially, may dry out or leak over time, requiring re-treatment. Polymers and resins offer a more durable, longer-lasting fill, but they can still be affected by heat, chemicals, or abrasion.

Types / Variations

Lubrication can be categorized based on the filling material used:

• Oiling: This is one of the oldest and simplest methods, often used for emeralds. Natural oils, synthetic oils, or specialized epoxies are used. Oiling is generally considered a temporary treatment as the oil can leach out over time, especially when exposed to heat or ultrasonic cleaners.
• Polymer/Resin Impregnation: This method uses synthetic polymers or resins to fill fractures. These materials are more durable than oils and can significantly improve clarity and stability. Common examples include materials like Opticon or various epoxies. This is frequently applied to stones like topaz, quartz, and sometimes diamonds with significant surface-reaching inclusions.
• Glass Filling: In some cases, a glass-like material is used to fill larger cavities or fractures, most commonly seen in certain types of treated sapphires or diamonds. This is a more permanent type of filling but can be brittle.

Grading & Quality Standards

There are no formal grading scales specifically for lubricated gemstones in the same way there are for color or cut. However, the quality of lubrication is assessed based on:

• Effectiveness of the Fill: How well the filler material conceals the fractures and improves clarity.
• Durability of the Fill: How long the filler material is expected to last without degrading or leaking.
• Type of Filler: Polymers are generally considered higher quality than simple oils due to their longevity.
• Visibility of the Fill: Ideally, the filler should be undetectable to the naked eye and blend seamlessly with the gem.

The Gemological Institute of America (GIA) and other major gemological laboratories will identify and report gemstone treatments, including lubrication, on their reports. This transparency is crucial for the trade.

Buying Guide

When considering a lubricated gemstone, buyers should:

• Ask for Disclosure: Always ask the seller if the gemstone has been treated, specifically if it has undergone lubrication or fracture filling. Reputable dealers will readily provide this information.
• Request a Lab Report: For valuable gemstones, insist on a report from a reputable gemological laboratory that details any treatments.
• Understand the Implications: Be aware that lubricated stones may have reduced durability compared to untreated stones of similar appearance. They may also have a lower value.
• Consider the Filler Type: Inquire about the type of material used for filling. Polymers generally offer better durability than oils.
• Check for Warranty/Return Policy: Ensure there is a clear return policy in case the treatment is not as described or deteriorates quickly.

Price Range & Value Factors

Lubrication generally lowers the value of a gemstone compared to an untreated stone of similar apparent quality. The degree of value reduction depends on several factors:

• Type of Gemstone: Lubrication is more common and accepted in certain gemstones like emeralds and topaz. Its impact on value might be less severe in these stones than in diamonds or rubies.
• Extent of Treatment: Heavily lubricated stones, where the treatment is obvious or necessary to make the stone even remotely attractive, will have a significantly lower value.
• Type of Filler: Durable polymer fills are generally valued higher than temporary oil fills.
• Original Quality: A heavily included, low-quality stone that requires extensive lubrication will still be less valuable than a naturally clean, high-quality stone.
• Market Perception: The overall acceptance and transparency of the treatment in the market influence value.

While treated stones can be more affordable, they represent a different value proposition than their untreated counterparts.

Care and Maintenance

Proper care is essential to maintain the appearance and integrity of lubricated gemstones:

• Avoid Heat: High temperatures can cause the filling material to expand, leak, or even degrade. Avoid placing lubricated stones in ultrasonic cleaners (unless specifically stated as safe by the jeweler), steam cleaners, or exposing them to prolonged direct sunlight or hot environments.
• Avoid Harsh Chemicals: Acids, strong detergents, and solvents can damage or dissolve the filling material. Remove jewelry before swimming, cleaning with household chemicals, or applying lotions and perfumes.
• Gentle Cleaning: Clean lubricated gems gently with a soft brush, mild soap, and lukewarm water. Pat dry with a soft, lint-free cloth.
• Professional Inspection: Have your lubricated gemstones checked periodically by a jeweler to ensure the filling is intact and to address any potential issues.
• Re-treatment: Some lubricated stones, particularly those filled with oil, may require periodic re-treatment to maintain their clarity. This should be done by a qualified professional.

Pros and Cons

Pros:

• Affordability: Lubricated gemstones offer a more budget-friendly way to acquire stones with enhanced visual appeal.
• Improved Appearance: They can significantly improve the clarity and brilliance of stones that would otherwise be considered too included or flawed.
• **Wider Availability:** Treatments make more stones commercially viable, increasing the selection available to consumers.

Cons:

• Reduced Durability: The filling material can be damaged by heat, chemicals, or abrasion, compromising the gem's integrity.
• Lower Value: Lubricated stones are generally worth less than untreated stones of comparable visual quality.
• Potential for Re-treatment: Some fills, especially oils, are temporary and may require costly re-treatment over time.
• Ethical Concerns: Lack of full disclosure can lead to misrepresentation and disappointment for buyers.

Common Misconceptions

Several misconceptions surround gemstone lubrication:

• All gemstones are treated: Not all gemstones undergo lubrication. Many beautiful and valuable gems are entirely natural and untreated.
• Lubrication makes a stone indestructible: While it can improve apparent clarity, lubrication does not inherently make a stone harder or more resistant to chipping and breaking. The base gemstone's hardness remains the same, and the filler itself can be a weak point.
• It's a form of dyeing: Lubrication fills existing fractures; it does not add color to the stone. Color treatments are a separate enhancement process.
• All fillers are the same: The type and quality of the filling material vary significantly, impacting durability and value.

Related Terms

• Fracture Filling
• Impregnation
• Resin Filling
• Oil Filling
• Glass Filling
• Gemstone Enhancement
• Disclosure
• Emerald Treatment
• Sapphire Treatment

FAQs

Is lubrication a permanent treatment?

It depends on the filler. Polymers and resins offer more durable fills than oils, which can degrade or leak over time and may require re-treatment. Glass filling is generally considered more permanent but can be brittle.

Can I clean a lubricated gemstone at home?

Yes, but very gently. Use lukewarm water, mild soap, and a soft brush. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can damage the filling material.

Does lubrication affect the color of a gemstone?

No, lubrication primarily addresses clarity by filling surface-reaching fractures. It does not add or change the inherent color of the gemstone.

How can I tell if a gemstone has been lubricated?

It can be difficult for the untrained eye. A professional jeweler or gemological laboratory can identify lubrication, often by observing the refractive index of the filling material or tiny air bubbles trapped within it under magnification. Full disclosure from the seller is the most reliable way for a buyer to know.

Is lubrication unethical?

The process itself is a standard industry practice. The ethical concern arises from a lack of full disclosure to the buyer. When treatments are clearly stated and understood, it is an accepted part of the market.