Irradiated Diamonds: Treatment, Process, and Characteristics
Irradiated diamonds refer to diamonds that have undergone a treatment process designed to change or enhance their natural colour. The irradiation process involves bombarding the diamond with high-energy particles, such as electrons, neutrons, or gamma rays. This exposure alters the diamond’s atomic structure, which in turn modifies the arrangement of its atoms and, consequently, its colour. The resulting diamonds can exhibit a wide range of colours, from subtle shades of green and blue to more intense hues such as yellow, pink, and even rare colours like violet.
Irradiation is typically used to improve or alter the natural colour of a diamond, creating hues that would otherwise be rare or unavailable. While some diamonds occur naturally in these colours, others require irradiation to produce or intensify certain shades.
The Process of Irradiating Diamonds
The process of creating irradiated diamonds involves several stages, which include:
Initial Diamond Selection: Not all diamonds are suitable for irradiation. The process is most commonly applied to diamonds that are either colourless or lightly tinted in yellow or brown. These diamonds provide the best results in terms of producing vibrant and desirable colours when exposed to irradiation.
Irradiation: During the irradiation process, the diamonds are exposed to a range of high-energy particles, such as electrons, neutrons, or gamma rays. The irradiation alters the structure of the diamond at a molecular level, creating “defects” in the diamond’s crystal lattice. These defects are responsible for the change in the diamond’s colour. The treatment can vary in duration and intensity, depending on the desired outcome.
Annealing (Optional): After irradiation, many diamonds undergo a second process known as annealing. Annealing involves heating the irradiated diamond to a specific temperature to further modify the colour. This step is essential for diamonds that are irradiated to achieve certain colours, as it helps to stabilise the colour change and deepen the hue. The annealing process also serves to enhance the overall appearance of the diamond, making it more vibrant and rich in colour.
Post-Treatment Assessment: After the irradiation and annealing treatments, the diamond is assessed for its final colour and appearance. It may undergo additional polishing or cleaning to ensure that the irradiation has not caused any damage or degradation to the diamond. At this stage, the diamond may also receive a certification or grading report that indicates its colour and any treatments it has undergone.
Colour Changes Resulting from Irradiation
The key goal of irradiating a diamond is to modify its colour, either to enhance its natural colour or to create a new, more desirable hue. Some of the most common colour changes resulting from the irradiation process include:
Green: One of the most famous and sought-after colours for irradiated diamonds, green is produced by exposing the diamond to neutron radiation. The green hue can vary in intensity from a subtle tint to a more vibrant shade, depending on the degree of irradiation and any subsequent annealing.
Blue: Blue diamonds can also be created by irradiation, although the process is slightly more complex than for green diamonds. The treatment process results in the creation of boron within the diamond’s structure, which gives rise to the blue colour. These diamonds are often very rare and valuable due to the distinctive hue.
Yellow: While yellow diamonds naturally occur in nature, irradiation can enhance or intensify the yellow colour, making it more vivid. The irradiation process may alter the amount of nitrogen within the diamond’s crystal lattice, which is responsible for the yellow colouring.
Pink and Red: Irradiated pink diamonds are among the rarest and most valuable diamonds in the market. The process used to produce these colours is highly intricate, involving precise control of irradiation and annealing. The colours achieved are typically soft pinks, though more intense reds can occasionally be achieved, depending on the diamond’s specific properties.
Brown and Grey: These hues are often created by subjecting diamonds to prolonged exposure to radiation, which creates complex lattice defects that result in brown or grey colours. These diamonds can be very affordable, but the hues are less sought after compared to more vibrant colours like blue or green.
Violet: Although extremely rare, violet diamonds can also be the result of irradiation, particularly when combined with specific heat treatment processes. These diamonds are highly coveted and can command high prices, especially when the colour is deep and intense.
Types of Irradiated Diamonds
Irradiated diamonds are typically classified into two main categories based on the treatment process:
Natural (Unenhanced) Irradiated Diamonds: These diamonds have undergone irradiation but have not been subject to any additional heat treatment. The colour change is a direct result of the radiation process, and these diamonds may exhibit more natural, softer shades. They tend to be less intense than those that have undergone further treatment but are still distinct in their appearance.
Treated (Enhanced) Irradiated Diamonds: These diamonds are subjected to both irradiation and subsequent heat treatment (annealing) to enhance the colour. The process is carefully controlled to achieve specific, vibrant colours, such as deep blues or rich greens. These diamonds are often more valuable than natural irradiated diamonds due to their enhanced hues and striking appearance.
Considerations When Buying Irradiated Diamonds
Certification: It is essential for buyers to ensure that irradiated diamonds are properly certified. Reputable gemological laboratories, such as GIA (Gemological Institute of America), will clearly disclose if a diamond has been treated, and provide full transparency on the treatment process. This allows the buyer to make an informed decision.
Price: While irradiated diamonds can be more affordable than their natural counterparts, prices can still vary significantly based on the quality of the treatment and the resulting colour. Diamonds with more vibrant and rare colours, such as blue or pink, may command premium prices. On the other hand, irradiated diamonds with more common hues, such as green or yellow, tend to be more affordable.
Durability: Irradiation does not affect the durability of a diamond, as the treatment does not alter the diamond’s physical structure beyond its colour. However, it is important to note that if the diamond undergoes excessive heating or improper treatment, the quality of the diamond’s surface or internal structure could potentially be compromised. It’s crucial to purchase irradiated diamonds from reputable dealers and laboratories to avoid issues with poor treatment processes.
Resale Value: The resale value of irradiated diamonds can be influenced by several factors, including the intensity of the colour, the quality of the treatment, and market demand for specific hues. While certain colours like blue and pink can be highly desirable, others like brown and green may be less sought after. Buyers should be aware that irradiated diamonds may not retain the same value as untreated diamonds of similar quality.