NRC requires that the initial import/distribution of reactor treated gemstones be by a distributor licensed by the NRC. After initial distribution, the gemstones will no longer be regulated ie subsequent distributors, jewelers and retailers do not need to be licensed.
NRC has also issued two distribution licenses for neutron treated Topaz (London & Swiss Blue) and is reviewing other applications.

Recently USNRC has issued a fact sheet wherein they have mentioned the following:

"The NRC has no reason to believe irradiated gemstones currently on the market are unsafe. The NRC has not requested that jewelers take these stones off the market.''

The NRC website(FAQs) clearly indicates  that there is no indication that wearing irradiated gemstones can be harmful and it further states that there is no reason to stop wearing blue Topaz. A study done by NRC estimated that a person wearing a blue topaz stone would receive an annual dose of 0.03millirem while a chest X ray is about 60 millirem ( thus a person receives 2000 times more radiation dose than wearing a Topaz for one year!)

Presently NRC does not have jurisdiction over gemstones that are treated in a Linear accelerator(LINAC) or by Gamma radiation. However, in the next few months, new rules will regulate LINAC treated gems. These will include requiring an NRC license for the importation of all blue topaz, red tourmalines, many beryls (treated blue, yellow, and pink colors, but not emerald), kunzite and irradiated diamonds. Cobalt-60 (gamma ray) irradiated gems such as various quartz colors, yellow sapphire and pearls are not affected by the upcoming regulations.