Do Natural Rubies Fluoresce?


All varieties of rubies fluoresce under ultraviolet light. “Corundum var. Ruby (fluorescent) in Zoisite,” Mundarara Mine, Arusha Region, Tanzania. © Rob Lavinsky, www.iRocks.com. Used with permission.
All varieties of rubies fluoresce under ultraviolet light. “Corundum var. Ruby (fluorescent) in Zoisite,” Mundarara Mine, Arusha Region, Tanzania. © Rob Lavinsky, www.iRocks.com. Used with permission.

Question

I was told years ago that natural rubies fluoresce but lab-grown rubies will not. Recently someone told me the opposite. He says that synthetic rubies fluoresce but natural stones won’t. Can you settle this?

Ken

Answer

All rubies fluoresce, whether they are natural or created in a lab.  Natural and synthetic ruby gemstones have the same chemical composition and physical properties.  However, there are slight differences in fluorescence patterns between natural and synthetic stones and even between natural rubies from different sources. For example, flame fusion is the most common way to synthesize corundum gems, which includes rubies and sapphires. Flame fusion rubies fluoresce stronger than natural gems. This can be used as a clue during identification.

The same ruby specimen shown above, now under normal white light. “Corundum var. Ruby (fluorescent) in Zoisite,” Mundarara Mine, Arusha Region, Tanzania. © Rob Lavinsky, www.iRocks.com. Used with permission.
The same ruby specimen shown above, now under normal white light. “Corundum var. Ruby (fluorescent) in Zoisite,” Mundarara Mine, Arusha Region, Tanzania. © Rob Lavinsky, www.iRocks.com. Used with permission.

In practice, it’s sometimes a very difficult determination to make.  However, when you have a tiny stone that doesn’t yield much information, every little bit helps.

Here is an overview of how some rubies fluoresce under longwave (LW) and shortwave (SW) ultraviolet light.

  • Myanmar (Burma) Rubies: LW strong red. SW moderate red.
  • Sri Lanka (Ceylon) rubies: LW strong orange/red. SW moderate orange/red.
  • Thai rubies: LW weak red. SW inert.
  • Flame fusion rubies (synthetic): LW very strong orange/red. SW moderate to strong orange/red.
  • Flux grown rubies (synthetic): LW Strong orange/red. SW orangey red and may have a blue tint or areas of blue.

I hope this helps to clarify things for you,

Don Clark, CSM IMG

Additional Comments On “Do Natural Rubies Fluoresce?” From The IGS On Facebook

© Jeffery Bergman, http://www.primagem.com. Used with permission.
© Jeffery Bergman, www.primagem.com. Used with permission.

Natural rubies fluoresce a bit. Natural Burma rubies GLOW!

Elaine Hochberg

The fact that raw hexagonal ruby crystals can fluoresce, and crystal cross-sections in matrix can also fluoresce, is a definitive answer.

Angel Brick

I have a number of rubies from Burma that are natural and they light up like a Christmas tree under UV light. They look very much like the rubies that Jeffery shared on this post. I can’t speak about synthetics since I’ve not tested one under UV light.

Jerry Anderson Jr.

Don’t forget that synthetic rubies have the same physical, chemical, and optical properties of a natural ruby so both fluoresce, more so with Burma rubies, though. That’s for sure.

Jennifer Simonds

“Ruby (fluorescent),” Jegdalek, Saroby, Afghanistan. © Rob Lavinsky, www.iRocks.com. Used with permission.
“Ruby (fluorescent),” Jegdalek, Saroby, Afghanistan. © Rob Lavinsky, www.iRocks.com. Used with permission.