Out of all of the gemstone treatments currently on the market there is one treatment that always raises questions. That treatment is irradiation. When the words “irradiation” are whispered the first thing that springs to mind is ‘is it safe’? The good news is yes it is. We will explore why gemstones are irradiated and what the NRC (Nuclear Regulatory Commission) do to ensure your safety.
The gemstone that has caused so much discussion is blue Topaz. Since the 80’s this gemstone has routine undergone irradiation to give it the blue color that we all know and love. There are two methods for irradiating blue Topaz. They both involve types of nuclear reactors. The first is to use a stream of electrons to induce the color, the other is to use a stream of neutrons. While the electron method produces Topaz that does not pose a hazard to humans the neutron Topaz can continue to emit radiation for years. After extensive research from various bodies including the NRC rigorous checks have been put in place to ensure all neutron irradiated blue Topaz that comes to market is safe to handle.
The below list gives an example of the colors that can be achieved with irradiation. This is not a complete list and other color variations are available.
There are three main ways to irradiate gemstones. Each method uses a different facility and can have different effects on gemstones.
The irradiation process can be thought of like balls. The neutron method fires large tennis balls at the subject and induces the color. The electron method uses tiny balls to fire at the subject. Gamma radiation uses microscopic balls with huge amounts of energy to induce the color.
The longer a gemstone is exposed to irradiation the more chance of the stone becoming radioactive. The reason why gemstones become radioactive is if impurities within the gemstone become active. Stones treated with either electron or neutron irradiation will remain radiaoactive for a period of time. Stones treated with gamma radiation will not become radiactive.
For stone treated with electron irradiation the radiation level of the material that comes out of the reactor is generally deemed safe to handle by the NRC. Even still there are strict guidelines in place to ensure that the Topaz is set aside for a number of months. Remember that radiation decays over time so if the stones are safe to handle straight out of the reactor they are safe to handle once they come to market.
Neutron radiation takes a longer period to become safe. According to the NRC the average time for freshly neutron irradiated Topas to become safe is 12 – 24 months.
Radiation is everywhere. It is a natural part of life and we actually can’t live without it. Lets do some quick comparisons. Radiation is measured by millirium or Radiation Absorbance Dose.
A 6ct Topaz worn for a year (assuming the radiation level is at the maximum that the NRC deem to be safe) = 0.03 millerium
Lets compare some other common thing (all based on 1 year exposure)
Obviously this is a very complex subject but lets try and explain it. I will explain the two ways gemstones get their color. Chromophores (impurities) and color centers (defects). Here we go
Chromophore. This is when a mineral has impurities which cause color. Take Sapphire for example. Pure Sapphire is clear. Add in Titanium as an impurity and it turns blue. Add in Iron it turns yellow. Add Chromium it turns pink. Add iron and Chromium and you get orange / pink (padparascha). This is the most common way gems get their color. So if you want to enhance a Sapphire, you can diffuse Titanium to the Sapphire and create a bluer stone (Surface diffusion).
Now lets look at Diamond. All Diamonds are pure Carbon. So how do they have pink Diamonds, yellow Diamonds and red Diamonds? The answer. A color center. This is a defect in the crystal structure of the gem. This defect causes color.
So if you take Kunzite, Topaz, Hiddenite, Diamond and try and induce a defect in the crystal lattice, you will induce color.
How do you cause a defect? You smash the atoms inside the crystal with something. This is where the electron radiation and neutron radiation comes in. You literally smash the gem with radiation to cause a defect which causes color.
These defects can be fixed by applying energy to the gem. In the case of Kunzite, this energy is in the form of UV radiation from the sun. The energy from the sun repairs the crystal structure and removes the pink color from the gem.
You will see plenty of irradiated Hiddenite in the market which has been irradiated. It has a color center induced which causes the green color. This color is sensitive to sunlight just like Kunzite.
The color in Topaz and Tourmaline for example is stable. The process for creating the blue color in Topaz involves irradiating the gemstone and then heating it. This heating process actually stabiles the color and creates a gem that will not fade or deteriorate over time.
Some of the brown Topaz you will see is the result of electron radiation of Topaz. If this Topaz is heated, it will turn blue and stablise the color. However a few years ago someone decided they would Irradiate Topaz but when it turned Brown with an orange tinge they decided not to heat it and turn it blue but to sell it as imperial Topaz. Sites like Gem Rock Auctions do not allow these types of stones to be sold as Imperial Topaz.
Now that you know how safe irradiated gemstones are it is time to decide if you really want to wear those false teeth. Afterall would you rather a set of false teeth or twice the number of Topaz gemstones.
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