RALEIGH, N.C. (WNCN/WCBD) — Millions of people have purchased special glasses to safely watch the solar eclipse that’s coming up August 21, but over the weekend Amazon notified some customers that the glasses they bought may not be safe.

Hucksters out there who are making counterfeits claiming they are real, but aren’t.

And trying to find real, certified glasses is becoming harder and harder because businesses that specialize in them are selling out.

People who want to view the eclipse are wary of fakes.

“I want to make sure I get the right glasses so I don’t cause harm to myself or my family,” says Christopher Jones who wants to watch eclipse safely.RELATED:Full coverage of the Solar Eclipse

American Paper Optics is making real and certified eclipse viewing glasses, but even they are falling victim to the scammers.

“One of our suppliers has a notice on their website, showing their glasses and a counterfeit one with their name on it,” says Sean O’Neal, the owner Science Safari in Cary which has been doing a booming business in eclipse glasses sales.

The warning on American Paper Optics website shows how to determine if the glasses you bought are counterfeits or the real thing.

The differences are subtle but important, like the shape of the eye piece and the hook that goes around the ear. Here is a link so you can study the differences for yourself.

“With real eclipse glasses you won’t be able to see anything until you look at the sun,’’ explains Allison Knox of Kelly Eye Care Center.

As the day of the eclipse draws closer, trying to find certified viewing glasses is getting more and more difficult.

The phone at Cary’s Science Safari is ringing off the hook with people looking for eclipse glasses, but O’Neal says he can’t get any more right now and is only fulfilling pre-pair orders.

“I’m trying to get up with my supplier to get more, but my 4,000 that came in this week are completely allotted,” says O’Neal.

Brandi Hudleston has her own glasses but came into Science Safari looking to buy a few pairs for a friend. She says she’s surprised the viewing glasses are sold out.

“I was a little shocked at how everybody is losing it over trying to find them,” she said.

Even online-retailer Amazon may have unknowingly sold counterfeit glasses. The company sent letters out to customers saying not to use certain glasses it sold because it can’t verify that they are certified.

NASA has an approved list of manufacturers who are making certified glasses with the code ISO 12312-2. That’s the international safety standard.

If you can’t get viewing glasses that you know are certified you can use an indirect way of watching. It’s called a pinhole camera. Here is a link on how to make one.