Emeralds-treatment
Transparency in Every Emerald
Emerald Treatments
Emeralds naturally form with many internal features—called jardin (French for “garden”)—which are small fractures and inclusions. These are part of the gem’s character, but they can affect transparency and beauty.
To improve appearance, most emeralds are treated with oils or resins that fill the surface-reaching fractures, making the gem clearer and more appealing.
Most emeralds are treated to enhance their apparent clarity.
Unlike rubies and sapphires, emeralds are never heat-treated to enhance color or clarity. Instead, emeralds are typically treated with oil or other fillers. The purpose of this is to draw the filling substance into any surface-reaching fissures (on a microscopic level) to improve the clarity of the emerald. Emeralds that have undergone no treatment are significantly more expensive. This will be specified in the certificate.
Emeralds, due to their formation in extreme geological conditions, often contain a significant number of inclusions — natural internal features or fractures within the stone. While these inclusions are characteristic of natural emeralds, they can negatively impact clarity and durability. To enhance their appearance and resilience, emeralds are frequently treated. Understanding these treatments is essential for buyers, as they affect both the beauty and the value of the stone.
Oil Treatment
Oil treatment is the most common and widely accepted enhancement for emeralds. The process involves filling surface-reaching fractures with a colorless oil, often cedar oil — a natural, non-toxic substance. This oil reduces the visibility of fractures, improves clarity, and enhances the stone’s overall appearance.
Purpose:
To minimize the appearance of fractures, enhance clarity, and help reinforce the stone’s structural integrity.
Types of Oil:
Cedar oil is the most commonly used due to its refractive index, which closely matches that of emeralds, making the treatment less detectable. Other oils, such as palm oil or synthetic alternatives, may also be applied, although cedar oil remains the preferred choice.
Stability:
Oil treatments are not permanent. Over time, oils can dry out, leak, or degrade, especially when exposed to heat, direct sunlight, or aggressive cleaning methods such as ultrasonic cleaning. Periodic re-treatment may be necessary to maintain the stone’s appearance.
Impact on Value:
Emeralds that have received only minor oil treatments retain most of their value. However, stones with moderate to significant treatments are typically valued lower. In rare and highly prized cases, emeralds may be completely untreated, significantly increasing their market value.
Detection of Oil Treatment:
Specialized gemological laboratories use magnification, UV light, and immersion techniques to detect oil treatments. Reputable institutions such as the Gemological Institute of America (GIA) and the American Gemological Laboratories (AGL) disclose the presence and degree of oil treatment on their certification reports, typically graded as None, Minor, Moderate, or Significant.
Resin and Polymer Treatment
Some emeralds are treated with synthetic resins or polymers instead of traditional oils. This process involves injecting a resin into surface-reaching fractures to fill them and provide additional structural support.
Purpose:
To improve clarity and enhance durability, especially in emeralds with more severe fractures than those typically treated with oil.
Types of Resins:
Epoxy resins and polymer-based fillers are commonly used. Unlike oils, these materials harden once applied, offering a more permanent solution for fracture filling.
Stability:
Resin treatments are more durable than oil treatments but are generally viewed as less desirable. They are harder to detect and reverse, and some resins may discolor over time, potentially altering the stone’s appearance.
Impact on Value:
Emeralds treated with resins are typically valued lower than those treated with oil. Among collectors and connoisseurs, resin-treated stones are often considered less authentic, and some markets may be reluctant to accept them.
Detection of Resin Treatment:
Advanced laboratory techniques such as infrared spectroscopy and UV fluorescence are often used to identify resin treatments. Under magnification, gemologists can sometimes distinguish resin-filled fractures by the slightly different sheen or luster they display compared to oil-treated emeralds.
Treatment Grading and Disclosure
When purchasing emeralds, it’s important to know the extent of any treatment, as it directly affects the gem’s market value and longevity. Reputable laboratories grade treatments as follows:
None: The emerald has not undergone any treatments, making it highly valuable and rare.
Minor: Only a small amount of oil or resin is used to fill fractures. These emeralds are considered high-quality and retain most of their value.
Moderate: A moderate amount of treatment is applied, often visible under magnification. While still beautiful, the emerald’s value is lower than that of untreated or minimally treated stones.
Significant: Extensive treatment has been performed, typically involving larger fractures and more visible treatments. These emeralds are usually more affordable but are considered less desirable by collectors.