On Monday, March 24, 2025, CIBJO, The World Jewellery Confederation, sent out a joint press release alerting members of the trade regarding an uptick in irradiated corundum (sapphire and ruby) with unstable color, “particularly sourced in Sri Lanka.”
The issue with irradiated sapphires and rubies is that their unstable (and more attractive) color will fade away, and not return.
1. Irradiated sapphire and ruby are reportedly being sold without proper disclosure. Test everything!
2. Stability testing is performed in all the major professional gem laboratories on a regular basis.
3. You can easily test for color stability in sapphires at your office desk. (see below)
According to the release, “the materials in question, which have a pleasing but temporary appearance, were earlier reported upon in a 2022 press release entitled ‘Irradiation of Rubies: a Cautionary Note.’” [RGNR – special thanks to Vincent Pardieu, one of three authors on that report, for sending us the link. You can read that report here! – gr]
Unstable Color – Both Irradiated and Natural Color
While it is possible to have unstable color in sapphire and ruby when irradiated, it is also possible that natural sapphires can also have unstable color.
As a general statement (in what can be a very long and complicated discussion), the basic problem with irradiated sapphire and ruby having unstable color is that once that irradiated enhanced color has gone, it is not coming back – that color was only temporary. So … for example: a beautiful irradiated ruby reverted back to its original very dark red, and will stay dark red… or that irradiated strong saturated yellow sapphire faded to very light yellow… and that strong saturated yellow is not coming back. (This is obviously the concern for being offered undisclosed irradiated sapphire and ruby.)
On the other hand, with natural sapphire having unstable color, the sapphire will get its color back. For example: A natural pink sapphire changes to an unstable pink orange-color, but then reverts back to its stable pink color. In fact, there have been several publications of articles specific to that topic, including: “Yellow Sapphires with Unstable Color,” by E. Billie Hughes, Gems & Gemology, Summer 2022, Vol. 58, No. 2, and “An Update on Sapphires with Unstable Color,” by Aaron C. Palke, Shane F. McClure, and Nathan R. Renfro at GIA, December 12, 2022 (seen here in the RGNR – December 2022).
The Letter
In a recent letter from the American Gem Trade Association (AGTA) addressed to, among others, the Sri Lankan Gem & Jewellery Association (SLGJA), AGTA expressed their concern, noting that “many U.S. dealers have been forced to stop purchasing yellow, peach, and Padparadscha sapphires, as well as rubies, from Sri Lankan dealers due to concerns about their color stability. A significant number of these gemstones are reportedly unstable, fading to almost white or light pink tones—or in the case of rubies, turning dark red over time.”
The letter went on to say, “it has come to our attention that some vendors may be using radiation from various sources to create temporary, undisclosed treatments. The AGTA and other industry associations strongly oppose these unethical practices, as they risk eroding consumer trust and diminishing demand for colored stones altogether.”
AGTA Raises the Alarm
We spoke to John Ford, AGTA’s CEO about the current concern. “Our members have been monitoring this for a while,” said Ford. “They saw this as an ever expanding problem.”
While color fading irradiated sapphires is not new, it is believed that not much of it has entered into the retail trade. But this is now their concern.
With improper disclosure, and few merchants performing in-house fade testing, AGTA is concerned for its members and the consumer. “Once we determined that there was a strong possibility, or that some of these goods were already being introduced to the trade, we wanted to slam the door on it immediately,” says Ford.
SLGJA To-Do List
In its response, the SLGJA said it would be working to put into place, several protocols, including the following:
▻ An Industry Awareness Campaign – focusing on the reputational risks associated with undisclosed treatments
▻ Strengthening Testing and Certification – working with leading Sri Lankan gemological laboratories to enhance color stability and radiation exposure testing
▻ Encouraging Full Disclosure – to ensure transparency across all transactions
▻ Policy and Regulatory Discussions – explore possibilities in stricter regulations and penalties for undisclosed treatments
▻ Collaboration with International Partners – ensure Sri Lankan gemstones/gem merchants continue to meet the highest standards of trust and authenticity
Color Stability Testing
Color Stability Testing (Also Known As Fade Testing) can be performed using a high intensity light source (approximately 150 watts). Making certain to keep the sapphire away from the heat of the light source, keep the light on the gem for approximately 4 hours.**
There were fade tests performed by Billie Hughes, noted in her report (above).
▻ “A fade test was conducted by placing the stone approximately 5 cm under a 120-watt incandescent spotlight for at least an hour, and a dramatic difference was observed. The color had changed from orange to a vivid yellow.”
SSEF – How is the colour stability of corundum tested?
According to the Swiss Gemmological Institute (SSEF), “Based on current scientific knowledge, the colour stability of gemstones can be quite easily tested – even by a well-trained gemstone dealer. Before testing, the colour of the gemstone has to be very well defined (e.g. with Munsell colour charts, Color Codex, or other colour matching systems). The stone is placed on a metallic reflecting plate and then exposed for several hours (minimum 3 hours) to a strong fibre optic light source (halogen). After this, the colour is again meticulously checked. Corundum with an unstable colour centre will display now a (slightly to distinct) shift in colour or saturation. To be very clear, this is actually the stable colour of the stone.
You can find a more complete SSEF description of Color Stability here.
**RGNR – Please do not randomly use this test on other gem species without doing your research.
