SA Jewellery Company profile: Wholesale of Jewellery and Gemstones
Colored Diamonds Treatment
Because of today's technological advancement, there are many treatments and improvements that can completely change the appearance of the diamond. These are specific modification performed on natural colored and white diamonds (usually already cut and polished), which are to improve the visual geological characteristics of the diamond, mainly improving clarity or changing the color.
Some of these methods can permanently change the diamond, while others are only temporary.
Treatments for enhancing clarity
Laser drilling - diamond manufacturers can employ lasers to remove or lighten a dark-appearing inclusion by drilling a tiny hole to the site of the inclusion. The laser may cause the inclusion to vaporize or the treater may apply bleach or acid to lighten the inclusion further. Laser drilling can make included diamonds more marketable, but the laser drill hole is considered a clarity characteristic. The drill-hole can fill with foreign material and become more visible. Laser drilling is considered a permanent treatment as the drill hole cannot be removed. Sometimes after drilling, the diamond may be fracture filled. Fracture filling - infusing molten leaded glass-like substance into a diamond’s fractures – is the most common diamond treatment used to enhance clarity. Fracture filling of surface reaching breaks can effectively disguise these features. It might also benefit a customer who accidentally cracks a diamond. The treatment can last for years with proper care, but the filling can be damaged during common jewelry repairs, or if subjected to repeated cleanings with steam, acid or ultrasonic. If the filler melts and leaks out, there is a possibility that it can be retreated. If the filler turns dark, it cannot be made colorless again. Fracture filling can make a diamond look more attractive, but also slightly lower its color.
Treatments for enhancing color
HPHT – The most widely known treatment for diamonds, combining high pressure and very high temperature. This treatment has been prevalent since a least the early 1950s. HPHT can make some brown and Type II diamonds more colorless, or can produce brownish yellow, orangy-yellow, green, blue, and even pink color. The color achieved through this process depends on the diamond selected for treatment. HPHT treatment is rarely detectable under a microscope and detection requires a qualified gemological laboratory. One of the first successes in detecting HPHT was the discovery by Bob Crowningshield of the GIA of the 595nm line, which along with other gemological properties, proved that the color had been treated. Laboratory reports would indicate "HPHT" as the "Treated" designation.
Irradiation - The process of irradiation entails bombarding diamonds with high-energy electron or neutron particles knocking carbon atoms out of place, physically altering the crystal lattice of the stone and causing a diamond’s color to change. Most commonly found colors in irradiated diamonds include green, blue, yellow and black diamonds. These diamonds will frequently exhibit an orange florescence and may have a higher concentration of color near the culet, the most likely place that a diamond is Irradiated in a lab. Irradiation treatment can usually be detected in a gemological lab with the use of a spectrophotometer. Lab report will show "Irradiated."
Annealing - this is a controlled heating and cooling process which is often used after irradiation to change a diamond’s color to brown, orange, or yellow. It has been reported to produce pink, red, and purple colors as well. When annealing is used by itself, it can change the color in a series – generally blue to green to brown to yellow. The treatment is stopped when the desired color is reached. If heat is later applied to an annealed diamond during routine jewelry repairs, it can drastically alter its color. Surface Coating - A thin layer of a colored material is deposited on the diamond in order to change its original color. When the coated surface is viewed under high magnification, the presence of trapped air bubbles, or worn areas where the coating has been scratched off, may be apparent. This treatment could be difficult to detect if the coating was applied only to the girdle or pavilion region of the stone, which is frequently the case. The treatment is not permanent. Lab report will indicate "Coated".
Synthetic Diamonds - Synthetic diamonds (also known as laboratory-created diamonds and laboratory-grown diamonds) are produced in an artificial process, as opposed to natural diamonds, which are created by natural geological events. Synthetic diamonds frequently utilize HPHTor CVD crystal formation methods. HPHT and CVD diamonds are virtually identical to natural diamonds, differences only become clear when they are analyzed in a gem laboratory.
CVD - Since 1954, diamonds have been grown inside laboratories in a variety of colors and parities. For growing gemstones, the most popular method is called chemical vapor deposition (CVD), which starts out with a tiny diamond "seed". Each seed is made of a repeating lattice of carbon atoms — just like all diamonds. The seeds are placed inside a microwave plasma oven. The oven zaps natural gas into a plasma of carbon, which sticks to each seed and slowly builds up a diamond, atom by atom. It can take anywhere from 10 to 12 weeks to bake up a batch of substantially sized diamonds.After the synthetic diamonds are grown to spec, they're cut into rough shapes with a high-power laser.After that, workers polish the synthetic gems for faceting like a natural diamond.
HPHT - The HPHT method for producing diamonds was first used by General Electric in 1954.Basically it mimics the natural process - the coal crystallizes in the form of a diamond through the intense heat and pressure occurring in the depths of the Earth.The HPHT process is very expensive, taking into account the energy and equipment required, The colored diamonds produced are mainly yellowish or brownish yellow.
To discover the advanced technologies to modify diamonds, requires the use of specialized equipment that can only be found in specialized diamond laboratories. Laboratory Certificate from a renowned laboratory recognized around the world is the only reliable source of colored or white diamond evaluation. In our opinion, the following four laboratories guarantee a reliable assessment of origin and value of Colored Diamonds......more