Tag Archives: fire test

Myths in Pearldom #3: The Flame Test

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:

  1. The “Flame Test” can be very destructive on pearls, both with lower quality (processed) pearls and very especially on “faux perles” or pearl imitations.
  2. Pearls and Imitations can become Hot after the use of the flame test: handle with caution.
  3. 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 …