Different gemstones exhibit a varied reaction to different types of treatments. One of the most popularly used treatments to produce brilliant gemstone is the process of irradiation. Light blue topaz gemstone turns into dark brown after radiation. The same brown topaz gemstone is reversed to its original blue colour by exposing it to a controlled heat treatment under specific conditions of temperature, pressure and catalysts.
What is irradiation?
Irradiation is just a miniature controlled nuclear attack on the gemstones. Imagine the crystal structure as the target, and a series of gamma ray bombs hit specific spots inside the gemstone. The bombardment of the gamma rays alters the colour of the gemstone significantly, without actually making little or no difference to other physical aspects like hardness or density.
Irradiation can lead to both addition and removal of certain ingredients in the structure leading to change in hue. There are certain colour centres within the crystal structure that give different shades when bombarded with gamma rays. That is why irradiation of gemstones is achieved not by trial and error, but using specific nuclear kits.
Does irradiation cause any kind of damage to the precious gemstone?
Basically, the process of irradiation is a great way to produce brilliant gemstones from rather disappointingly dull stones using no physical force. When the gamma rays hit the colour centres within the crystal structure, the cells are knocked out in a random motion. The systematic process of irradiation can produce brilliant colours which are permanently restored and made more attractive by exposing the stone to heat and pressure.
Is irradiation a permanent process?
The fact that gemstones irradiated using gamma rays are produced under intense temperature makes them a permanent item to wear. The colour is long sustaining and can possibly be reversed to its original shade by applying an equally high bounty of energy. It is certainly an irreversible colour transformation process as far as irradiated gemstones like topaz are concerned.
Is irradiation a costly affair?
Of course it is! Otherwise, all the blue topaz available in the market would look like brown speckled stones with absolutely no commercial viability. Almost 95 percent of the blue topaz are irradiated and treated with heat before they get their signature shade.
Irradiation is done using highly powerful nuclear bombardment machines that cost millions. Only organizations having certificate to operate a nuclear machine can use it. Moreover, it requires skilled gemologists and operators who understand both aspects of gemstone properties and nuclear physics.
Thus, the cost of irradiation of gemstone is a pricey affair. But it ensures that the end consumers get only high quality gemstone produced from natural extracts and polished by skilled professionals.
Are there certificates to tag irradiated stones?
Yes, there are different certifications offered across all continents to ensure gem quality. It also ensures that none of the gemstones have turned radioactive. The major certifying units are GIA, AGS and other renowned gemstone research labs.