“We are seeing oiled stones outside of emerald every single day in the lab, and yet there is so little awareness about it in the market.” – E Billie Hughes, Lotus Gemology, Bangkok
Well, THAT caught our attention!
And it came just days after the SSEF issued a Trade Alert warning that some emeralds are being cleaned, submitted to laboratories, and then re-filled before being sold with the earlier lab report.
That alert focused specifically on fracture-filled emeralds.
Hughes pointed us in another fracture-filled direction.
It was about how often fracture filling is encountered in gemstones other than emerald, and how surprised many people in the trade still are when they hear about it.
Gary Roskin
Roskin Gem News Report
Just a One-Off?
Was this simply one laboratory’s experience?
Or was it something the broader gemological community was seeing?
So we reached out to several other international gemological laboratories.
And what we found was eye-opening.
Although each expert answered independently, they all told us essentially the same story.
“Any Stone with a Fracture…”
Shane McClure, Director of Colored Stone Services at GIA, didn’t hesitate.
“Whenever I do a presentation on clarity enhancement, I always make a point of saying multiple times that any stone with a fracture can be clarity enhanced.”
That simple statement may be the most important point in this discussion.
Fracture filling isn’t just an emerald treatment. It’s a fracture treatment.
McClure noted that filling Paraíba tourmaline has become commonplace, tsavorite garnet is also commonly filled, and while tanzanite rarely contains fractures, those that do are often filled. Over the years, GIA has also encountered filled materials ranging from ruby to rhodonite—and many other gem species in between.
A Principle Every Laboratory Agrees On
Dr. Michael Krzemnicki, Director of SSEF, echoed exactly the same principle.
In the laboratory’s 50th Anniversary publication, SSEF 1972–2022, he writes:
“The matter is actually very simple. Any gem material with fissures is prone to be treated with a fissure filler to reduce the visibility of fissures… Astonishingly, the understanding of this basic concept has only penetrated the trade when it comes to emeralds.”
SSEF has documented fracture filling in rubies, sapphires, spinels, Paraíba tourmalines, garnets, and even rarer gem materials. Yet Krzemnicki notes that the laboratory has not observed any notable increase in such treatments in recent years.
The Fissure Is the Key
Chris Smith, President of the American Gemological Laboratories (AGL), approached the subject this way:
“Fundamentally, any stone with an open fissure may be clarity enhanced with an oil or other material (wax, resin, etc.).”
Among the filled gem materials AGL most commonly encounters, in addition to emeralds, are copper-bearing tourmalines, unheated rubies, red beryl, alexandrite, spinel, rubellite tourmaline, unheated sapphires, and garnets.
Then came perhaps his most telling observation.
“…at various times, literally every gemstone type and variety…”
Smith notes that AGL has reflected this philosophy in its reporting for years. Since redesigning the laboratory’s reports in 2009, fracture filling has been treated as an additional enhancement that is evaluated and disclosed regardless of gemstone species whenever detected.
SSEF – “Minor oil in fissures”
Estimate: 300,000 – 500,000 CHF
Lot Sold: 691,200 CHF
Rubies Too.
Daniel Nyfeler, Managing Director of the Gübelin Gem Lab in Lucerne, offered a similarly matter-of-fact response.
“Those you mentioned, plus rubies of course. Once in a while a random oiled tanzanite, a garnet…”
Beyond the Laboratory Report
Nyfeler also shared examples of Gübelin’s informational sheets that accompany certain laboratory reports. Rather than simply reporting test results, the additional sheets help clients understand what those findings mean in practical terms—whether an emerald contains fissures that could later be filled, or whether it is naturally fissure-free and therefore not susceptible to clarity enhancement.
“Fracture filling is a reversible and repeatable treatment,” says Nyfeler. “This means that a stone can be (partially) cleaned before being submitted to a laboratory for testing and then refilled afterwards. Selling such a stone with a report that is no longer current is misleading and may constitute fraud.” He goes on to say that, unfortunately, this practice does occur. “Buyers can reduce this risk by requesting that the seller instruct the laboratory to ship the stone directly to the buyer immediately after testing.”
Gübelin currently issues two different informational sheets for emeralds, depending on the stone’s condition at the time of examination:
1. “For all emeralds which have fissures but no clarity enhancement at the time of testing, we are issuing an additional document that emphasizes the temporary nature of the absence of fissure filling.”
2. “And for all emeralds which have no fissures and hence obviously also no clarity enhancement, Gübelin issues a different info sheet, emphasizing that for this specific quality, the stone is not susceptible to any fissure filling.”
Looking ahead, Nyfeler notes that, “In relation to our Gübelin Gemstone Rating system, we are currently thinking about granting bonus points (like we do for corundum qualifying for a trade colour) for such fissure free emeralds. This is a rare quality in emeralds, and their immunity about a possible undisclosed treatment gives peace of mind to the client.”
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Different laboratories.
Different continents.
Same story.
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SSEF Has the Documentation
Perhaps the strongest evidence that fracture filling beyond emerald is not a new phenomenon comes from SSEF’s own published research.
Over the past decade, the laboratory has documented:
- 2017 — Oil in rubies.
- 2018 — Artificial resin in rubies.
- 2018 — Artificial resin in Brazilian Paraíba tourmalines.
- 2022 — An entire chapter titled Fissure Filling in Emeralds and Other Gemstones in SSEF 1972–2022.
- 2026 — Fracture-filled spinel.
- 2026 — The recent Trade Alert on re-filled emeralds accompanied by outdated laboratory reports. (seen here)
Lotus Gemology Has Been Documenting It for Years, Too
The observations from Lotus Gemology are hardly new either. Over the past decade, Billie Hughes and the Lotus team have published numerous articles documenting fracture filling in a wide variety of gemstones, including:
- 2015 — Laboratory Alert: Oiled Gemstones
- 2017 — Oiled Ruby (red oil / dye treatment)
- 2020 — Oiled Spinel and Tanzanite
- 2022 — Oiled Apatite: Before-and-After Documentation
Taken together, the Lotus articles reinforce what every laboratory contacted for this story told us independently: fracture filling extends well beyond emeralds and has been documented across a growing range of gem materials for years.
Even GIA Was Talking About It Nearly a Decade Ago
Not surprisingly, the same message appears in GIA’s literature.
In a 2016 Gems & Gemology article discussing clarity-enhanced tourmaline, Arthur Groom—co-developer and one of the pioneers of the ExCel clarity enhancement process—remarked that fracture filling in tourmaline “is nothing new.”
Groom explained that Paraíba, rubellite, and bicolor tourmalines had long been candidates for fracture filling because their value made the treatment economically worthwhile. Properly disclosed, these treated gemstones continued to find acceptance in the marketplace.
That observation, made nearly a decade ago, aligns closely with what laboratories continue to report today.
Amongst the many articles and Gem Notes published by GIA, the most interesting/curious reports on fracture filling include:
- Fall 2009 – Polymer-Filled Aquamarine
- July 31, 2015 – Blue Chalcedony Partially Filled with Epoxy Resin
- July 22, 2020 – Glass-Filled Burmese Star Ruby
- September 3, 2021 – Transparent Rhodonite with Clarity Enhancement
- February 2, 2026 – Fracture-Filled Diamonds Detected in Mounted Jewelry
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As our timeline shows, the laboratories are not suggesting
that fracture filling is suddenly becoming common in every gemstone.
They’ve been publishing it for years.
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Picture 3: Heavily filled fissures appear completely concealed,
often showing characteristic colour flashes. – Gübelin Gemmology
Christopher P. Smith and Shane F. McClure
The Laboratories Have Been Talking for Decades. Has the Trade Been Listening?
As far back as 2002, Shane McClure and Chris Smith co-authored the Chart of Commercially Available Gem Treatments in GIA’s Gems & Gemology (Winter 2002), documenting clarity enhancement across numerous gem species. More than two decades later, laboratories around the world are still delivering the same message.
As Smith reminded us while reviewing this article, the conversation didn’t begin in 2002. For many gemologists, discussions about fracture filling have been part of lectures, laboratory reports, and conversations with the trade for decades.
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Seen here (left) is the Winter 2002 issue of GIA’s Gems & Gemology, Vol. 38, No. 4, pp. 294 – 300, and accompanying pull-out chart. Inside this issue is a Gübelin and GIA joint publication (written and produced by then Gübelin’s Christopher P. Smith and GIA’s Shane F. McClure) Chart of Commercially Available Gem Treatments
This chart details the generalized use of clarity enhancement to reduce the visibility of fissures,
as well as its occurrence in gem species including beryl, chrysoberyl, corundum, diamond and others.
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And that brings us back to Lotus Gemology and Billie Hughes.
Hughes says she regularly speaks with clients who are surprised to learn that fracture filling extends well beyond emeralds.
“Some of my clients that buy in the field tell me they won’t make an offer on a stone now without putting it in some alcohol first.”
This is gem testing in the field—simply experienced buyers recognizing that fracture filling has become important enough in certain gemstones to influence purchasing decisions.
Looking Beyond Emerald
For decades, emerald has dominated conversations about clarity enhancement. Perhaps that’s understandable.
Emeralds are frequently fractured, and the trade has developed well-established terminology and disclosure standards around oil, resin, and other fillers.
But the laboratories contacted for this article all agree on one point.
If a gemstone contains an open-reaching fissure, fracture filling is a possibility.
Ruby.
Paraíba tourmaline.
Spinel.
Sapphire.
Garnet.
Alexandrite.
Red beryl.
And, of course, emerald.
Or something else entirely.
The Buck Stops With You
The science isn’t new.
The laboratories have been documenting it for years.
Perhaps it’s time we stopped thinking of fracture filling as an emerald treatment.
We routinely examine every gemstone to determine whether it’s natural or synthetic.
Perhaps it’s also time we routinely examine every gemstone to determine whether it’s been fracture-filled.
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