What is Artificial Irradiation or Irradiated Diamond?



An irradiated diamond is a natural diamond that has been exposed to a radiation treatment in order to turn the stone into a different color. Irradiated diamonds can be found in many different colors including, blue, green, pink, yellow and orange. Colored diamonds do occur naturally, however, they are more rare than white diamonds. This makes it difficult to meet the buying demand and significantly drives up the cost of colored diamonds. Artificial irradiation helps meet the demand of colored diamonds and creates an affordable alternative to naturally colored diamonds. 

Artificial irradiation dates back to the early 1900s, when chemist and physicists, Sir William Crookes, discovered that the color of a diamond exposed to radium salts was drastically altered-turning from yellow or brown to green. Although the exposure to radium salts resulted in an enhanced color change in the diamond, there were several flaws that made Sir William Crookes processes infeasible.  

The cost and difficulty of obtaining radium kept Crookes technique from becoming a widespread treatment. An even greater disadvantage was the treated diamonds developed dangerous levels of residual radioactivity, making them unsafe to wear. In fact, one study by a 1940s engineer, John Hardy, shows that nearly 30 years after Crookes exposed a diamond to radium salts, the diamond was still radioactive! By the 1950s, artificial irradiation processes had been developed that could change the color of a diamond without making them radioactive for long periods afterward.  

GIA Irradiated Diamonds

Artificial Irradiation

Diamonds can be divided into five types: Type l, Type la, Type laA, Type laB, Type lb, Type ll, Type lla and Type IIb. Type l and Type ll are the most common diamond. The classifications are based on their Nitrogen content, how they transmit ultraviolet light, and by their infrared absorption spectrum.  

Type I diamonds contain nitrogen. About 98% of cuttable natural diamonds belong to type Ia, and about 0.1% of gem diamonds belong to type Ib (with significantly lower nitrogen concentrations of approximately 40 ppm) in which isolated atoms are randomly distributed in the diamond’s lattice. Diamonds in which no nitrogen can be found, with the help of infrared spectroscopy, belongs to Type ll. Type ll account for around 2% of all gem diamonds. If the stone does not possess any electric conductivity, it is a Type IIa. These are transparent to UV light up to around 225 nm, contain relatively free elements, and in general are colorless. Type IIa diamonds are often in the upper range of the color grades. Lattice distortions caused by deformation during the growth process may also produce yellow, brown or even pink Type IIa diamonds. Type IIb diamonds make-up only about 0.1% of all gem diamonds. They are typically blue or greyish-blue and are semi-conductors. The type of diamond, and the natural color of a diamond, greatly determines the  

Today, the most common methods of artificial irradiation include neutron and electron bombardment. Through these processes, high-energy particles are blasted at the diamond, knocking carbon atoms within the stone out of place and producing a colored diamond. Neutron bombardment typically results in a green to black colored diamond, while electron bombardment creates a blue, blue-green, or green color. To further alter the color, the stone may also go through an annealing process, in which the heat turns the irradiated stone into hues of pink, yellow, orange or brown. 

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