Transcript for Undercover Bachelor: Diamonds
Many say that when you meet that special someone you just know and some might even say the same applies when picking out that special ring. But the aborted choosing a diamond than meets the -- and beneath the surface these precious stones may not always be with they seem. Earlier this summer my colleague Dan Harris went undercover to find out what he can judge to diamonds by its cover. -- -- -- Best day of my life. This setting with beautiful and the bride clearly out of my league young doctor named Bianca and looked extremely hot. The only stressful part of the entire experience was buying the perfect engagement ring. Think about it this is probably the most emotional purchase of your life. So how do you know if you're really getting what you think your five. The play in the -- is PGA right. Or an undercover -- -- -- -- this see how upfront dealers really are I have reluctantly agreed to Wear a disguise. And smells like her from time like go undercover as a bachelor on the hunt for rain are they making a -- Abraham Lincoln vampire slayer. Little footnote here finding a credible this -- can be -- like somebody like this is going to be buying a diamond -- more like you know bear trap. Finally we decided solos that -- the -- again feeling -- -- business this. For our undercover shopping center -- producer Aaron he's gonna play the role of Mike fictional girlfriend's best friend he'll be carrying a hidden camera. And this woman will play the role of my supportive mom. -- where cameras to. And -- -- -- is actually an internationally renowned gem and jewelry expert. You look carefully -- explained to me something she says every shoppers should be aware. It is a little known industry practice -- goes by the attractive name clarity enhancement. Through fracture -- and here's what it it manufactures take a less desirable -- As naturally occurring cracks -- and after a high tech procedure they still those cracks in. -- band with a led based less than those old cracks then disappears in a naked eye. This done becomes more attractive than looks like -- higher grade diamonds. Does that look like pretty -- like a great sense in us it's a beautiful set for Friday. Visa vick's -- diamonds typically sell for about thirty to 50% less than comparable untreated diamonds and there's. Nothing wrong with find that I know people who want to bigger. No one -- for the bucks. So there's a problem sellers sometimes don't explained what it is and why it seems like you're getting a discount. Unfortunately. There argue for his troops -- without disclosure in the -- until revealed Wednesday. In -- you get what you pay for. Or less. So we've decided to test how opening dealers are about it. Our destination is New York city's fabled diamond district the country's largest marketplace for -- it. This is a shop called -- USA. My undercover -- has already told Alex here that are three grand budget and interest in something around one carry this is going to. -- -- -- -- I notice none of -- -- he says clarity enhancement. -- No mention of -- in -- so I asked directly. -- fire in him. You know right. Alex today that's the policy what. He's not well -- and Alex. Moves off topic here is good policy reviews -- -- program. So I ask him why is it's a good deal them to us. For myself anything I should know about special care anything -- clarity enhanced diamonds might not withstand repairs that require high -- Just make sure that's. I think it's only here assigned I think -- should know that it isn't really wearing that night. All -- money. So I fork over the cash and later Alex brings a significant and -- 9700. Dollar appraisal which makes our diamond look like an even bigger mark. We -- out the door with our brand new -- and back in the studio. And ring. Does look beautiful. Down here it says that there filled. -- grades are based on appearance after clarity and announcement. Feathers in other words what crack or fracture and here it says -- doesn't say with want. To find out exactly what is inside our brand new -- We take into an independent lab for analysis here and X ray fluorescence spectrometer determines its composition. It's been clarity enhanced. If this was not fissure filled -- the probably would have been down more in the imperfect range. The test shows it is filled with a high lead content glass -- -- now it's time for our own surprise I'm to go back to the store in disguise. This scene with they have to say and to reveal who -- are. We tell Alex the results of our independent testing. If there's any clarity in ten minutes filling -- We're the last ten days. And that can't you. I -- rehearsal. You don't know Larry Hansgen join eluded us citizen owes apology that's designed. It's time to tell these guys who we really aren't Croats -- less -- if that's president. You're right so today. Not my mom this is. And an amendment didn't again anger and we have this look at my experts and he is fractured -- did not want to. US anybody I -- -- -- Larry. -- -- policy -- that's not true. But that's the first sunny and even know -- even tell me. You really don't know -- clarity I think no idle policy process that's definitely I don't know what we're does that put it. Something that maybe you don't understand what you're selling. Why don't you just -- resulting -- Have been apologies defects journal part of the stone visit work gets done. -- -- -- -- -- -- -- -- -- -- -- -- -- -- Plus the inside -- he's polished he's. But that's different. I did say it was this is one of those emotional purchases and then we'll make it. Don't you have a special responsibility never to tell me everything about this there. Many people don't know that that might mean pants on there then the owner going to I think that he didn't know was enhanced by asking you didn't do you might do you have it on camera before as a matter. After we -- the video he tells us about the -- I want to go against that thing refitted for. Resides in me like yeah plus and didn't include direct -- footprint and I was never. So something you want someone -- there were welcomed the New -- and they're right should check. Overall we -- we not doing anything to misrepresent and view maybe it was a misunderstanding. -- when I asked whether he thinks the sale was deceptive he gets angry that our cameras are rolling don't think what exactly. I don't think we're fictional. I don't know I don't think this is its ability to live and then -- -- It's your property. Okay you must legally no -- -- you came late king Hussein was trying to being put faithfully visited. -- -- -- -- -- Indiana he -- our money back and offers to help must find a new damage but his two year old school friends. Sorry about. But very thank you having your. For Nightline this is Dan Harris.
This transcript has been automatically generated and may not be 100% accurate.