Post by lamaMama » March 25th, 2012, 10:58 am
Dear all,

A few months ago I saw a wonderful deal on Groupon website: for just 79$ (shipping included), one could get themselves "an 18-inch pearl necklace in a choice of eight colors from My Pacific Pearls’ online store (a $450 value)". Along with the pearls I was promised “care instructions and a certificate of authenticity and valuation. Groupon customers also receive two $50 vouchers toward future purchases from the wide array of jewelry on the My Pacific Pearls website; the vouchers must be used in two separate orders, each totaling at least $100.”
I figured that I got nothing to lose, and as long as the pearls that come are not an absolute obvious fraud, I'd like to own a string. Thus, I went into this fully aware that I do not expect high quality. I should also put a disclaimer that I am not an expert in pearls or other jewelry. I am, however, an expert in a variety of laboratory techniques that can tell me a thing or two about what I got on hand.
I am prompted to write this now, as I see Groupon has posted another chance for its subscribers to purchase a great deal from [url][/url]

The website promised:
    Pearl Size: 9mm - 10mm
    Luster: Very High
    Nacre: Very Thick
    Surface: Very Good
    Pearl Shape: Near-Round to Round
    Matching: Very Good
    Number of Pearls: 45 - 50 Pearls Individually Double-Knotted
    Grade: High Quality AA+
    Species: Freshwater
    Design: Classic, Elegant, Timeless
    Occasion: Formal, Evening Wear, Business Wear, Weekend
    Rarity: Popular
    Clasp: Genuine 14K White Gold Filled Safety Clasp
    Stringing: Double-Knotted Double Strand Fine White Silk
    Necklace Length: 18 inches which can be extended to 19 inches at the clasp

The pearls arrived within a month of order placement via regular USPS mail envelope. The velvet pouch enclosing the necklace started to gracefully disintegrate in my hands, leaving behind a dusty black powder. A certificate of authenticity was attached with some horrendous dollar value identified as the official price of the pearls. The two $50 vouchers are still – months later – nowhere to be seen.
I have in my possession a necklace with a single Akoya pearl in it – this one was bought for a few hundred bucks from and given to me as a present by my mother. It served as my comparison baseline.

First thing first – I took out my digital calipers. The size of pearls ranged from 8.22mm to 9.71mm, with average value of 8.92mm. So if we squint a bit, we can believe the promised 9-10mm.

I am not an expert, and will not even attempt to judge. See a very poor picture below

According to wiki, nacre is made of calcium carbonate and is the essence of the pearl – what the mollusc actually coats the irritant that is embedded in it. (Source: Over time, the nacre is expected to form thicker and thicker on the surface of the pearl, as the irritating pearl inside a mollusk is kept there longer and longer.
Using an X-Ray Fluorescent (XRF) machine I can tell composition of the object I am looking at by shooting X-rays and getting a characteristic signal back from the depth of up to ~0.05mm. Both my Akoya pearl and the pearl strings from My Pacific Pearls showed calcium (this tool is unable to detect carbon to verify calcium carbonate, but seeing calcium is good enough on its own. Not that many other things have calcium). So yes, we do have nacre on there. It is possible that the nacre is thinner than the 0.05mm that this machine can penetrate, but the plastic bead would not be detected by this instrument due to lightweight elements used in plastics.
Most of the pearls on the market today are cultured pearls, meaning that an irritant was introduced inside a mollusk at one point in time over which the current pearl was grown onto. I have read somewhere that X-ray imaging should be able to show the delineation between the original bead and the nacre formed on top, since the two materials will have some difference in density. In fact, this was true of my Akoya pearl which appears to have about 0.5mm of nacre on the surface of the 4.5mm diameter base bead. No such delineation was seen on the pearls from this necklace. Based on the resolution of the X-Ray machine I used, I expect the thickness of nacre on these pearls to me <0.02mm

I was told that the surface would be ‘very good’. This is hard to judge, unless you have experience, which I do not. Comparing the surface of this strand to the Akoya pearl I have, a few key differences are clear. The surface of the $79 necklace contained flaws: occasional surface depressions that extended a good 0.2mm into the pearl; small dimples; lines of discoloration. The Akoya pearl is close to perfect with no such defects.

As promised, it is near-round to round. No complaints there.

Well, all the pearls in the strand are similar in their defects, although clearly no two are the same. They do match well. I should note that no one, even after being specifically asked to do so, could distinguish flaws on these pearls while standing at a comfortable talking distance (a few feet) from me. Everyone, however, was able to notice the imperfections I described under ‘surface’ once holding them and getting very close to them.

47 pearls. Right between 45 and 50, as promised


No comment, since I can’t judge.

Wiki to the rescue: what is a ‘gold filled clasp’? says that this is finishing technique where gold is bonded to the surface of a base metal under heat and pressure. It also says that “gold-filled items are 50 to 100,000 times thicker than regular gold plating”. (Side Note: HELLO – plating can be done almost to any thickness desirable from few tens of nanometers to tens of microns (granted, the latter one is much more expensive). Boo-hoo on Wiki) Nevertheless, this means that I should be able to detect gold on these clasps using an X-Ray Fluorescence machine I used to detect calcium on the pearls.
Well, unfortunately, no gold here. There is copper, a tiny bit of tin. A little bit of further analysis with an Energy Dispersive X-Ray Spectroscopy (EDS) detector mounted inside the Scanning Electron microscope (SEM), and I could clearly tell that we have SnPb plating as the surface finish.

I was promised double-knotted fine white silk. What I got is in fact double knotted, and was white. But it is not silk. The difference between natural fibers such as cotton and silk, and their modern synthetic counterparts can be easily seen by a burn test. Natural fibers, once lighted, leave behind ash that can be easily brushed off and the ends of the strand will appear neat and trim. The polyester and nylon strands, however, will bead-up and form a brown/black ball at the end of the strand – and this is precisely what we are seeing here. Both ends of the My Pacific Pearls necklace appear to be burnt nylon strings.
Yes, indeed the necklace is 18” long

All in all, I would say I got what I paid for. I would rather see Groupon modify their claims on their promotion to reflect the fact that the product does not come with a 14-kt white-gold filled clasp and a promise of $50 coupons. I would also like to see [url][/url] retract the statement on their web page claiming‘thick’ nacre, silk strand, and gold-filled clasp.

Sometime in the future I might want to have these pearls re-strung with real silk strand and an actual decent clasp. At that time I might choose to keep one pearl out to cross-section it to see the actual thickness of the nacre on the pearl.
An overview of the Classic White Princess necklace from
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Close-up of the clasp and pearls of the Classic White Princess necklace from
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Comparison of X-ray images of Akoya pearl from and Classic White Princess necklace from The Akoya pearl clearly has ~0.5mm of nacre, while the princess necklace does not have visible nacre.
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A close up image of the string on the Classic White Princess necklace from The end of the string is burnt, indicating a synthetic material.
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