And here we are back in the saddle and readying to continue with the Ultraviolet light test series. Since there are many varieties of pearls to compare I have chosen to separate them into groups based mainly on their COLOR. And why do it this way? because it just seems so simple and obvious, and although many people will say there is not much in common between an Australian South Seas Pearl (SSP for short) and a Chinese Freshwater pearl (CFWP, also for short) –I mean, the differences are jarring: SSP are produced in the sea with a Pinctada maxima pearl oyster, and most CFWP are grown in rivers/lakes/ponds with Unionidae pearly mussels- they have a very similar color and overall look.
Still, each group will have its own sub-group for analysis and comparisons, so as not to cause much discomfort among those that prefer to keep their apples apart from their oranges. So, shall we jump into the tests?
White Pearl Group: Akoya, SSP and CFWP
In this group I decided to include the most common pearls in the World, just with CFWP and the saltwater Akoya pearls you can say you’re reaching well over 95% of the World’s production of cultured pearls. White South Sea Pearls (SSP), which include Australian and Indonesian productions, are far less abundant and larger-sized than its counterparts, but their color is very similar in a silvery white variation. Let us place these pearls next to each other and compare their look:
The similarities in the overall look of the pearls is more than evident, but on close inspection there are subtleties that are revealed: pearls are not like other gemstones and we should not expect sharp, dramatic differences but their beauty is more in the realm of “the little things”. Some can be revealed by close inspection with a loupe/triplet, using a special background and light situation or by immersing them in water (The Water Test). On the photo above you may notice that the pearl on the left (an Akoya Pearl, sometimes called “Mikimoto” or “Japanese” Pearl) has some interesting “stripes” (faint ones, these are the stripes you can see in the mother-of-pearl nucleus; you can see these due to this pearl’s thin nacre coating), that the middle pearl (a Chinese freshwater pearl) has a yellowish-pink tint and the one on the right (an Australian South Sea Pearl) has a greenish tint to it. Some of these features are due to the LED lamp I used to shoot the photos, but they are not as evident in a normal light situation. Anyway, I employed the same light (and distance from it to the pearls) for all this study, so all pearls are subject to the same treatment.
So, how will these pearls react to long-wave UV light exposure? Let us see and compare.
As you can see, the Akoya and Freshwater pearls (left & middle) have a remarkably similar glow (pure white-blue) and the South Seas one (right) has a greenish-blue cast to it. One thing we have to keep in mind for he rest of this series is that every UV lamp, background setting (I recommend a black cloth) and ambience light (a darkened room is best), you employ can affect the results so you may see something different from these results. Finally, these are photos and our eyes are better at capturing the glow/fluorescence effect.
Akoya Pearls
I used 3 different Akoya pearls now to see additional results on this group. I had a very white Akoya, a cream-beige (“golden”) Akoya and a “black Akoya” (irradiated) pearls for this group. Results were quite interesting.
On the image above you will be able to see several things, but first I want to point out the most evident one: a small Chinese Freshwater pearl (CFWP) which I call “the blank pearl” (the “PC” is to be used for Spanish as “Perla China”) and this is something I will do an all UV photos that do not include a CFWP. What for??? It will serve us to compare the standard blue-glow of the “standard pearl” with others. That is the reason you’ll see it there.
Anyway, the white Akoya has the expected color but now we see 2 interesting things: the golden Akoya has a very faint glow –almost none- and it is of an golden-orange color, whereas the “black Akoya” has no glow at all. For the most part fake/imitation pearls display no fluorescence (but I have seen some that do). What does this mean to us? That dyed pearls will not glow the way a pearl does, and that the golden-yellow pigments somehow interfere with fluorescence as well. Interesting isn’t it???
Freshwater Pearls
In this instance I have some traditional freshwater pearls for inspection. I skipped the normal shot because they are simply unremarkable…just plain white pearls. Their glow is the one we quite expected: the beautiful blue glow.
Conclusion & Closing Remarks
White pearls glow with a beautiful blue-green glow under long-wave Ultra-Violet light, but some pearls of the “white pearl” group may not display this fluorescence, this would include some (I can’t say that all until I can check thousands of pearls) of the golden and dyed/irradiated pearls.
What have I missed? I do not have any “Blue” nor “Pink” Akoya pearls for testing, and there are many cheaply dyed freshwaters pearls that I should include in these tests too. I will, as soon as I have samples. If you care to share your personal research or to send me samples I will be more than happy to update this entry to include your personal findings. Please feel free to write to us by means of the “Comments” section.
Stay tuned for the next group: Black Pearls.
Orient & Overtones on Pearls.
Orient:A remarkable phenomenon produced by light being reflected and refracted by the pearl layers, which produces an inner glow. The finer the pearl layer (aragonite crystal), the better the orient of the pearl. (Source)
In these pictures we can see that both Black and Mexican pearls have a special sheen that makes it appear as if that they display various colors and that they do not display just one color…as seen on the other pearls. These “color rings” that seem to float on the pearl are known as “overtones” -when seen on dark colored pearls- and as “orient” on light colored pearls. At this time we will not talk about what causes this unique optical effect to manifest, but we will discuss this another time, but we will talk about using this visual attribute to differentiate pearls.Water Test on Light Colored Pearls.
Now, we introduce these same pearls in water and the change is significant: both the imitation pearls and the freshwater pearl had no change and are even “whiter”, but the pearls in the Gulf of California display a pair of color rings. Here we see the pearl’s orient easily:
Water Test on Dark Colored Pearls:
Now, let us look at the same pearl but inside water …
In the case of both the dyed pearl and the Tahitian black pearl, the overtones make a stronger appearance than what can be seen on those same pearls with a naked eye. All three imitation pearls are devoid of overtones, but some would be confused with the “Shell Pearl” because in the photo you may see something similar to a ring, but it really is not … overtones are truly a dynamic visual effect that is best seen personally or in a video. Mexican pearls are noted for their overtones: a true visual spectacle.Comparing light and dark pearls in Water:
From left to right: Akoya pearl, freshwater pearl, black pearl and dyed freshwater pearl
Imitation or Fake Pearls:
Pearls from the Sea of Cortez:
The Video.
Learning tricks of the trade is something that we have done since we began researching, back in 1993, and this of course not only involves pearl oysters, but their magnificent product: the pearl. But a thing that has always bothered us are “fake pearls” or imitations. For this reason we have come up with this series. Some time ago, back in 2004, Manuel, Enrique and I took several pearls and imitations and filmed a video of their reaction to the famous “flame test”. Bibliographic sources mentioned that the artificial or false pearls burn on contact with fire, while real pearls can survive this process without damage or with minor damage. So, are we to just blindly believe in this? Let’s try it and see what happens!!! And this video was the result of this experimentation. The results surprised us too, but if we obtained important information. So please watch this video first:
Results
We learned several things when “playing with fire.” The first one is that pearls, both authentic and imitation, obey “Murphy’s Law” in the sense that even if they look “OK” to touch they are not: they become extremely hot! and thus are difficult to manipulate with your fingers right after the 7 seconds under an open flame. So, if you plan to perform this little experiment on your own, use some tweezers and caution to manipulate the pearl. But for now, let’s describe the results, pearl by pearl:
Freshwater Pearl:
The first pearl to undergo the flame test was a freshwater-pearl of Chinese origin. This pearl was submitted to artificial staining to acquire a dark color and it even had a good appearance, since it even had good iridescence. But after only seven seconds under fire we noticed the following changes:
1. The pearl’s drill-hole was severely affected, its nacre becoming almost pulverized, this in effect extended the drilling area (made the drill hole larger). The pearl’s surface was seriously damaged, like the damage caused by the sun and the environment in an oyster shell after about 10 years of exposure.
2. The pearl displayed small cracks in various parts of its surface, which radiate or spread from small “bubbles” that formed in the pearl’s surface. Before the flame was applied, these were non-existent.
3. The pearl lost much of its luster and color, becoming duller and less appealing.
Chinese (Dyed) Freshwater Pearl on the "Flame Test" - Before and after comparison
So we can conclude that artificially colored pearls (or those that have been subject to some types of processing such as bleaching) are more sensitive to fire and can be destroyed with the flame test… but not burned. The ash or soot on the pearl is easily removed with a rag.
Test Results: Not Passed (or 50% passed).
Naturally Colored Cortez Pearl:
Our Pearls are never subjected to any “embellishment” processes; this actually means that they are never polished, nor bleached, nor dyed … so it was not strange that the “flame test” -in the same 7 seconds time-span as that of the Freshwater pearl- had no visible negative effects: we could find no cracks, no little “bubbles”, no change in the pearl’s appearance. What was most striking was to see that it was more difficult to remove the soot from of this pearl. Finally, there was no perceptible change in the of nacre around the pearl’s drill hole, nor in the pearl’s luster or its color.
Test Result: Passed!
Flame Test on Gulf of California Pearl
Imitation pearl: “Shell Pearl”:
Before discussing the results I want to explain something about these imitations. They are the best imitations we have had a chance to see and analyze. Many suggest that “Mallorca pearls” are the best, but we believe these imitations are superior for several reasons:
1. Have a center of ceramic, which gives them a good weight … like a pearl.
2. They have several layers of paint or varnish. Each layer is of characteristics and two of these layers are semi-translucent so give an effect that is added on the base color layer. The final layer is apparently a protective layer and gives the “sheen” or luster to the pearl. Layers of “color”, in green and purple-are printed in a translucent coating using a “newspaper” or dot-matrix style, thus these two colors seem to “float” on top of the jet-black color that coats the ceramic bead. What do I mean by this? Consider using the image below for better understanding.
Comparison of Tahitian Pearl (right) and Black Shell-Pearl (left)
These imitations (for information on their manufacture process, see here) caused a “craze” in the year 2000. In that year, they were successfully introduced into the market through the famous Gem, Watch & Jewelery Fair, and many were misled by these very good imitations. Pearls that were “affected” by these imitations were the Tahitian black pearl and white South Sea Pearls of Australia. As you can see in the photos, it is very easy to confuse these pearls with a naked eye.
"Baby" SSP (left) vs Shell-Pearl (right)
And although they are very good imitations … they do feel fake when you touch them: this is where they just “lost their magic.” Certainly, a high quality pearl is difficult or impossible to imitate, but for most pearls … specially those that are subject to rutinary processing and end up with a uniform look, imitations will be somewhat easy to produce.
Burned Shell-Pearl
Well, let’s get to the results: the “Shell Pearl” required twice the length of time (14 seconds) under the influence of the flame in order to burn in a manner proper for imitations, this due to its protective outer-cover, which protects it from chemical and mechanical damage, and it seems to have a fire retardant effect . However, this outer-coating can become damaged easily (with scratches) and this facilitates the burning of the “pearl”. In the video you can see how this imitation suffers from severe damage on its surface layers and a yellow-colored area affected will be seen on the area affected by heat.
Test Result: Failed!
Cheap Imitation Pearl (Plastic)
This kind of imitation is the one usually found in most economic products, such as in rosaries, small girls “jewelry” and economic bijoux jewelry. In this case the product is made out of plain plastic beads (polyethylene) with a simple paint covering. They are recognized immediately as false by their appearance, for its light weight and the presence of tell-tale “chips” (since these are usually made with molded plastic, they will have these), worthy of any product of very poor quality.
There is really is not worth talking about these imitations … in just 7 seconds under a flame they will burn and light up, we’ll have thick black smoke and the piece will end up as a small mass of molten plastic. The they are are the most fun to burn!!!
Test Result: Failed!
Mallorca or Majorica Pearl:
This is the famous “pearl”, which everyone wants to try with this test. First of all an external analysis: I can tell you that the external texture of these imitations is usually rougher than that of a real pearl. This imitation is quite successful with “Akoya” pearls (produced in Japan and China), since these pearls have little variety of colors (mostly in the white, yellow and cream-beige range) and their shape is almost always round and in sizes from 6 to 9 mm indiameter. Again: the more “clone-like” the pearls become after processing, the easier it is to imitate them.
The “Majorica Pearls” are made with a glass bead that -supposedly- has been made using “real pearl powder”. Even if this were true, it hardly matters because this can never be observed under the coat of paint. The “paint coatings” of these imitations are made using a “special recipe” which includes sardine (fish) scales (using a “special treatment”) which is referred to as “Pearlescence”, and several coats of this varnish are applied to this glass bead, which also must be “baked” or dried using special procedures (including UV light). This matters little after 8 seconds under fire: the layer of varnish is burned and left with a terrible appearance… leaving exposed areas of a white glass bead behind if you try to remove the sooth and carbonized paint.
Majorica Pearl before (top) and after (bottom) the Flame Test
Test Result: Failed!
This video (in Spanish) depicts the manner in which these “faux pearls” are made (and it seems that they are no longer producing these imitations in Mallorca, Spain):
Conclusions:
- The “Flame Test” can be very destructive on pearls, both with lower quality (processed) pearls and very especially on “faux perles” or pearl imitations.
- Pearls and Imitations can become Hot after the use of the flame test: handle with caution.
- Pearls can become damaged with heat and fire: they are organic gems and they have some water in their composition, so do avoid these to ensure for proper care of your pearls.
Coming soon: Demystifying other pearl myths …