Professional Jeweler Archive: Maybe Mabe

September 2002

Gemstones & Pearls/Gemology


Maybe Mabé

Thousands of fake mabé pearls were released into the U.S. a few years ago. Nobody noticed until recently


Those magnificent mabé pearl earrings you stocked a few years ago might come back to haunt you. “Fakes were quietly passed into the American market in large quantities in the mid- to late 1990s,” says Sarabeth Koethe, Ph.D. and G.G., of Gem-Sciences International, Deer Park, CA, a specialist in natural pearls.

Koethe discovered the problem when a customer asked her to change the mountings of her mabé earrings. As she started the work, a cap resembling a contact lens came off the pearl. “Obviously, this doesn’t happen with real mabé pearls,” she says.

Mabé pearls are formed in a mollusk a pearl farmer is going to retire, she says. The farmer inserts several mother-of-pearl pieces into the skin next to the shell. When covered with nacre, they’re cut from the shell, with their beauty determined by nacre thickness, pearl color, size and surface uniformity.

With the fake mabés Koethe examined, the top of the cap (the one facing the viewer) effervesced to hydrochloric acid, a test sometimes used to help identify organic products such as natural and cultured pearls. The mystery deepened when she tested the inside of the cap, which theoretically should have effervesced also but did not. The concave surface of the cap contained a painted-on frosty surface. “These turned out to be assembled fakes,” says Koethe. “When they came apart, the paint on the inside of the cap started to craze, crack and peel.

Further investigation proved the part under the cap was a plastic dome held in place with adhesive. The backing was plastic also. (Real mabés are backed with mother-of-pearl). She says the fakes came in two primary colors: cream rosé and golden.

The cap itself was found to be polycarbonate – which explains the effervescence.

Size of the Problem

Koethe informally surveyed the market and alerted major gemological laboratories of the problem with the mabés. She reordered mabés from the same supplier used by her client’s jeweler. “All were fakes,” she says. She also ordered mabés from Eastern, Western and Southern U.S. pearl dealers. All were fake. At Tucson’s gem shows that first year, Koethe saw dealers with bags full of mabés, many on sheets with 20 to 30 each. “These too were fakes,” she says.

Since then, however, she hasn’t seen fake mabés at Tucson and hypothesizes that whoever made them stopped after being discovered. If you take into consideration quantities sold at Hong Kong shows also, she says, sales could easily have reached into the millions of units. “Given what it probably took to make these, I’d say it probably represented one of the largest profit margins in the industry.”

Koethe says major gemological laboratories may not have been aware of the deception because mabé pearls are rarely sent for identification.

Challenges of Identification

Revealing the deception is straightforward when the components are shown or when the pearl is sawn in half. Identification isn’t so easy when the pearls remain intact and assembled. But Koethe says there are some things to look for:

  • Fake mabés have plastic backs that don’t effervesce to hydrochloric acid. (Note: HCL is considered a destructive test and shouldn’t be used without customer consent).
  • Real mabés have genuine mother-of-pearl backs. Look for irregularities or a bit of the brown skin of the shell to help identify them.
  • Fakes are very uniform in shape, color and outline. Real mabés generally are far more irregular. Stay away from sheets of 20-30 mabés.
  • In 1996/1997, prices ranged from $100-300 per pair for fakes. Good-quality matched real mabé pairs in similar sizes ranged from $1,000-$1,500, says Koethe.
  • With magnification, Koethe can sometimes spot air bubbles or ripples around what would be the juncture securing the mother-of-pearl backing to the body of the “pearl.” “You’re looking through a substance that’s clear but glued at the end,” she says. “These clues aren’t evident in real mabés.”

Koethe says it would be wise for jewelers and appraisers to keep a set of real mabé pearls on hand for comparison and to send suspect mabés to a lab for proper identification.

• Gem-Sciences Int’l., Deer Park, CA; (707) 968-0636.

– by Robert Weldon, G.G.

Genuine mabé pearls like these generally are irregular and hard to obtain in exact matching pairs. These are courtesy of KCB Natural Pearls, San Francisco, CA.
Bottom, from left: These fakes come from pearl dealers in the South, East and West. Courtesy of Gem Sciences International.

Photo by Robert Weldon.


Components of the fake mabé pearls. At left is a plastic dome covered by a broken piece of polycarbonate shell. At center is a broken piece of polycarbonate. At right is a slab of faux mother-of-pearl plastic used as a base.
At 10X , the paint used to coat the convex surface of the polycarbonate is peeling off and crazing. Courtesy of Gem Sciences International.

Photo by Robert Weldon.

This illustration shows the cross section of a fake mabé pearl.

Illustration by Orasa Weldon.

A 10X photo of the inside of the polycarbonate shell shows paint or lacquer that forms a frosty surface and is prone to peeling. While the top of the shell effervesces to hydrochloric acid, this painted surface doesn’t.

Photo by Robert Weldon.

Copyright © 2002 by Bond Communications