Jewelry Market

The World of Gemstone Treatments: Unveiling the Secrets

August 2, 2024
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Gemstone treatments are processes applied to enhance a gemstone's appearance or durability. Common treatments include heating, irradiation, dyeing, oiling, and coating. Heating, for instance, involves subjecting a gemstone to high temperatures to improve color or clarity. Irradiation uses radiation to alter color, while dyeing introduces artificial color. Oiling fills cracks with oil or resin, and coating applies a thin layer to the surface. Each treatment impacts a gemstone's value differently, depending on disclosure. While these processes can enhance beauty, understanding them is crucial for making informed purchasing decisions.

What is gemstone treatment?

A gemstone treatment is any process applied to a gemstone to enhance its appearance, durability, or value. This can involve a variety of techniques, from simple heating to complex chemical processes.

Which Treatments Are Used to Improve Gemstones?

While there are numerous treatments, some of the most common include:

Heating:

Heating is a gemstone treatment process that involves subjecting a gemstone to high temperatures to alter its color, clarity, or both. The goal is typically to enhance the gemstone’s appearance.

Countries Involved in Heating Gemstones

While the practice of heating gemstones is widespread, some countries are particularly known for their expertise in this area. These include:
• Thailand: Renowned for its expertise in heating rubies and sapphires.
• Sri Lanka: Also a significant player in the heating of sapphires and rubies.
• Madagascar: Known for heating various gemstones, including sapphires and zircons.

While not a primary center for heating, the US has facilities for heat treating diamonds.

How Does Heating Work?

The specific process varies depending on the gemstone, but generally involves the following steps:
1. Gemstone Selection: Suitable gemstones are chosen based on their potential for improvement through heating.
2. Heating Process: The gemstones are placed in a controlled environment and subjected to high temperatures. The duration and temperature vary depending on the desired outcome.
3. Cooling: The gemstones are slowly cooled to prevent cracking or damage.
4. Inspection: The treated gemstones are examined to assess the results of the heating process.

How Does Heating Affect a Gemstone’s Value?

The impact of heating on a gemstone’s value is complex and depends on several factors:
• Disclosure: If the heating process is disclosed, it typically has a minimal impact on the value, especially if the treatment has improved the gemstone’s appearance significantly.
• Undisclosed Treatment: If the heating is undisclosed and discovered later, it can significantly diminish the gemstone’s value.
• Quality of Treatment: A well-executed heating process that enhances the gemstone’s beauty without compromising its integrity can positively impact its value.
It’s important to note that while heating is a common practice, not all gemstones respond positively to this treatment. Some gemstones may experience color changes, clarity reduction, or even damage if heated improperly.

What Are the Most Common Gemstones Treated with Heat?

Heat treatment is a common practice in the gemstone industry to enhance color, clarity, or both. Here are some of the most common gemstones that undergo this process:

Corundum (Ruby and Sapphire)
• Ruby: Heating can improve the color intensity and remove unwanted inclusions.
• Sapphire: Heat treatment is widely used to enhance the blue color, remove unwanted yellow tones, and improve clarity.

Quartz Group
• Amethyst: Heating can convert amethyst to citrine.
• Citrine: Some natural citrine is actually heat-treated amethyst.
• Smoky Quartz: Heating can lighten the color to produce a golden or citrine hue.
Other Gemstones
• Topaz: Heating can improve color and clarity.
• Aquamarine: Heat treatment can remove greenish hues and enhance the blue color.
• Tanzanite: Heating can improve color and clarity.
It's important to note that while heat treatment is common, not all gemstones of a particular type undergo this process. Many natural gemstones are available without any treatment.

Irradiation

Irradiation is a gemstone treatment process that involves exposing a gemstone to radiation to alter its color. This process is achieved by bombarding the gemstone with high-energy particles or waves.

How Does Irradiation Work?
The irradiation process typically involves the following steps:
1. Gemstone Selection: Suitable gemstones are chosen based on their potential for color enhancement through irradiation.
2. Irradiation Process: Gemstones are placed in a controlled environment and exposed to radiation. The type of radiation (gamma rays, X-rays, or neutron bombardment) and duration vary depending on the desired color change.
3. Cooling and Stabilization: After irradiation, the gemstones might need a cooling or stabilization period to ensure the color change is permanent.
4. Inspection: The treated gemstones are examined to assess the results of the irradiation process.

How Does Irradiation Affect a Gemstone's Value?

As with heating, the impact of irradiation on a gemstone's value depends on disclosure:
• Disclosed Treatment: If the irradiation is disclosed, it typically has a minimal impact on the value, especially if the treatment has improved the gemstone's appearance significantly.
• Undisclosed Treatment: If the irradiation is undisclosed and discovered later, it can significantly diminish the gemstone's value.
It's important to note that while irradiation can enhance the color of gemstones, it doesn't always produce stable results. Some irradiated gemstones may experience color fading over time, especially when exposed to light. Additionally, some irradiation methods can induce radioactivity in the gemstone, which requires a cooling-off period before the gemstone can be safely handled.

What Gemstones Benefit from Irradiation Treatment?

While heat treatment is more prevalent, irradiation is also used to enhance the color of certain gemstones. Here are some common examples:
• Topaz: Irradiation is widely used to create blue, pink, or other colors in topaz.

• Aquamarine: Irradiation can intensify the blue color of aquamarine.
• Diamond: Irradiation can create various fancy colors in diamonds, such as blue, green, or yellow.
• Amethyst: Irradiation can sometimes be used to enhance or change the color of amethyst.
• Citrine: Irradiation can be used to create a deeper orange or reddish color in citrine.
It's important to note that not all gemstones of these types are irradiated, and many natural, untreated stones are available.

Dyeing Gemstones

Dyeing is a gemstone treatment process that involves introducing artificial color into a gemstone. This is typically achieved by soaking or immersing the gemstone in a dye solution.

What Are the Most Common Gemstones Treated with Heat?

Dyeing is most commonly used on porous gemstones that can absorb the dye. These include:

• Turquoise: Often dyed to enhance or restore color.
• Opal: Can be dyed to create various colors.
• Coral: May be dyed to enhance color or create different hues.
• Amber: Sometimes dyed to create deeper colors.

How Does Dyeing Work?
The dyeing process typically involves the following steps:
1. Gemstone Selection: Porous gemstones suitable for dyeing are chosen.
2. Dye Preparation: A dye solution is prepared with the desired color.
3. Dyeing Process: The gemstones are soaked or immersed in the dye solution for a specific period.
4. Drying: The gemstones are dried to remove excess dye.
5. Inspection: The dyed gemstones are examined to assess the color intensity and uniformity.

How Does Irradiation Influence a Gemstone's Price?

• Disclosed Treatment: If the dyeing is disclosed, it typically has a minimal impact on the value, especially if the treatment enhances the gemstone's appearance.
• Undisclosed Treatment: If the dyeing is undisclosed and discovered later, it can drastically reduce the gemstone's value.
It's crucial to note that dyeing can affect the gemstone's durability. The dye may fade over time, especially when exposed to light or chemicals. Additionally, dyeing can sometimes mask internal flaws or fractures.

Oiling Gemstones

Oiling is a gemstone treatment process where a colorless oil or resin is filled into cracks or fissures within the gemstone to improve its appearance. The oil or resin has a refractive index similar to the gemstone, making the fractures less visible to the naked eye.

Which gemstones are commonly treated by oiling?

Emeralds are the most well-known gemstones treated with oil. Their inherent nature with inclusions and fractures makes oiling a common practice to enhance their clarity and overall appearance.

Other gemstones that may undergo oiling include:
• Aquamarine: Can be oiled to improve clarity.
• Opal: Sometimes oiled to enhance its play of color.
• Ruby: Occasionally oiled to fill minor fractures.

Which countries are involved in oiling treatment?
While specific data on countries primarily involved in oiling gemstones is limited, regions with significant emerald and gemstone processing industries are likely to be involved. Colombia, for instance, being a major source of emeralds, is likely to have a strong presence in oiling these gemstones.

How Does Oiling Work?
The oiling process generally involves the following steps:
1. Gemstone Selection: Gemstones with visible fractures or inclusions are chosen for oiling.
2. Oil Preparation: A suitable oil or resin with a refractive index similar to the gemstone is prepared.
3. Oiling Process: The gemstone is immersed in the oil or resin, allowing the liquid to penetrate the fractures.
4. Drying: Excess oil or resin is removed, and the gemstone is dried.
how does oiling treatment affect on gemstone's value?
The impact of oiling on a gemstone's value depends on disclosure:
• Disclosed Treatment: If the oiling is disclosed, it typically has a minimal impact on the value, especially if the treatment has significantly improved the gemstone's appearance.
• Undisclosed Treatment: If the oiling is undisclosed and discovered later, it can significantly diminish the gemstone's value.
It's essential to note that oiling is not permanent. The oil can evaporate over time, especially with heat exposure or ultrasonic cleaning, reducing the gemstone's clarity. Additionally, while oiling can enhance the appearance of a gemstone, it does not improve its durability or hardness.

Coating Gemstones

Coating involves applying a thin layer of material to a gemstone's surface to alter its appearance. This can include changing the color, enhancing brilliance, or creating special effects.

What Gemstones Commonly Are Treated by Coating?
While coating can be applied to various gemstones, it's particularly common on:
• Diamonds: Coatings can enhance a diamond's color or create unique effects like iridescence.
• Tanzanite: A cobalt coating is often applied to enhance the blue color.
• Other gemstones: Some gemstones may be coated to improve their appearance or create specific effects.

What Countries Are Involved in Coating?
Coating technology is relatively advanced, and the process can be conducted in various countries with advanced manufacturing capabilities. Major jewelry hubs like the United States, Switzerland, and Japan are likely to have facilities for gemstone coating.

How Does Coating Work?
Coating typically involves the following steps:
1. Gemstone Preparation: The gemstone's surface is cleaned and prepared for the coating.
2. Coating Application: A thin layer of material, such as metal oxides, is applied to the gemstone's surface using techniques like vapor deposition or sputtering.
3. Curing: The coating is cured to ensure its adhesion and durability.

How Coating Affects a Gemstone's Value

The impact of coating on a gemstone's value depends on several factors:
• Disclosure: If the coating is disclosed, it typically has a minimal impact on the value if the treatment enhances the gemstone's appearance.
• Undisclosed Treatment: If the coating is undisclosed and discovered later, it can significantly diminish the gemstone's value.
• Durability of the Coating: Coatings can wear off over time, affecting the gemstone's appearance and value.
• Type of Coating: The type of coating and its impact on the gemstone's overall appearance will influence its value.
It's crucial to note that coatings can alter the gemstone's optical properties, and they may not be as durable as the gemstone itself. Additionally, some coatings can interfere with gemstone testing methods, making identification more challenging.

Conclustion

Gemstone treatments offer a fascinating glimpse into the world of gem enhancement. From the ancient practice of heating to modern techniques like coating, these processes have the power to transform raw materials into stunning jewels. While this article provides a foundational understanding, the world of gemstone treatments is vast and complex. To delve deeper into specific treatments, their impacts, and the ethics surrounding them, explore our comprehensive articles on Artemies Gems and Jewelry.

Note: most of pictures are from GIA

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