Detecting diamond treatments and synthetic diamonds are a challenge to the entire industry. Some diamonds treatments are more challenging than others to identify. Here are the main diamond treatments and synthetics to know about.
Synthetic diamonds are identical to natural diamonds in their chemical characteristics. Methods to identify these exist and while they can be challenging and sometimes require expensive equipment, they are not thought to be a significant threat. However, very small diamonds that are set into jewelry can be much more difficult to determine their origin. Several diamond imitations, most notably cubic zirconia and synthetic moissanite, also exist. Neither of these poses great challenges in identification for an experienced jeweler or gemologist.
When diamonds have black inclusions, they may not be very appealing to the eye. A process for removing these black inclusions developed in the 1960s and had widespread use by the 1970s. First, the laser is focused on an inclusion and a microscopic drill hole is left behind. This allows an acid bath to enter the diamond and remove the black imperfections. Although this is done in an effort to improve the appearance of the diamond, one can debate whether it really does since it leaves a drill hole and white inclusion where there used to be a black inclusion. Most laser drilling is easy to identify. However, some newer methods are more challenging since they do not leave a drill hole. Pricing is erratic. Some will lower the price of the diamond due to the drilling process, while others will not, arguing that the diamond may still have the same clarity grade but with slightly improved appearance. The important thing here is disclosure. In the U.S., it is required to disclose all diamond treatments. As long as consumers know what has been done, it is then up to them to make an informed buying decision.
HTHP is the abbreviation for “High Temperature, High Pressure.” This treatment was perfected in the early 2000s for changing the color of a diamond using nothing more than controlled heating combined with high pressure. These expensive presses are effective on some diamonds and can change the color from a low yellowish or brownish color all the way up to D, E, or F colorless. The same process can also be used to change some diamonds into fancy color diamonds such as intense yellow or other colors. Detecting this treatment is the most challenging in the industry. Sometimes, microscopic signs are left behind that can be proof positive of the treatment. But other times, there are no signs. Sophisticated equipment can act as screeners for these treatments.
Irradiation of a diamond is used strictly to create fancy color diamonds from off-color inexpensive diamonds. The process is controlled and stable. Resulting colors can be a wide range including green, yellow, orange, pink, and even red. Some irradiated diamonds are relatively easy to detect with simple tests and magnification while some require more extensive testing and equipment.
Clarity Enhancement is a process involving the use of a lead-based glass that through heating and pressure, is imparted into the diamond, effectively hiding the feathery type of inclusions. The film-like layer of glass is so fine and minute that it does not add significant weight (if any at all) to the diamond. The process is very effective in masking these inclusions. The correct term for this treatment is clarity enhanced, though many in the trade prefer to use the term “fracture-filled.” Diamonds do not have fractures that are being filled; they are cleavages (feathers), and gemologically speaking, there is a difference. As long as the treatment is properly disclosed, it again is up to educated consumers to decide if this product is for them.
It also is important to note that the treatment may not be stable. Care should be taken with these diamonds. They should not be placed in an ultrasonic cleaner. If repairs are to be done by a jeweler, the jeweler should be informed about the treatment as the high heat generated by a jeweler’s torch would damage the filler. It can be retreated if this should happen.