Fissure-Filled Rubies

For Your Staff:Selling Treated Gemstones

Fissure-Filled Rubies

Rubies often are heated to remove haziness and improve color. Sometimes a glassy substance seeps into fissures, fractures and cavities during this process. Here's how to tell customers about it

This is eighth in a series of articles in Professional Jeweler on how to explain gemstone enhancements honestly and positively. The series began with emerald in June 1998.

Whether unintended or by design, one side effect of heat-treating rubies to embellish their color is that fissures and cavities are sometimes filled with a glass-like substance.

Corundum, the species of mineral that produces ruby, is routinely heated at or near the source, often in antiquated heating devices. More modern heating units reach temperatures close to the melting point of corundum: 2050° C. Both environments may contain borax or alumina powders, thought to even out temperatures and prevent heat-related cracks.

However, these powders fuse at high temperatures and form a type of molten glass that permeates surface-reaching cracks or fissures. While its presence is minuscule in fissures, it can actually gather and add weight in larger pits or cavities. These glass-filled areas may be apparent under magnification because ruby and glass have different refractive indexes and the glass may have more surface scratches and undercutting because it's softer than ruby.

Introducing Enhancements
When you talk to your customer about ruby enhancements, you might point out these gems have been heat-enhanced for centuries. Heating rubies can deepen or lighten certain colors and enhance clarity (see Professional Jeweler,July 1998, pp. 123-124). Simply explain to customers the filling of ruby fissures as a consequence of heat treatment is also common. The process does several things:

  • It seals up surface-reaching fractures and pits that may have occurred naturally. This diminishes the fissure's visibility and unsightly appearance.
  • It enhances transparency.

In cases where the ruby's integrity, especially its weight, increased because of glass filling, you should explain this fact to customers. It's also important to point out the vast difference in price between untreated rubies and those that are heated or fissure-filled. Prices for comparable looking stones may vary tens of thousands of dollars per carat!

It's up to you to gauge your customers' needs and interests. But it's also your responsibility to help them make the most informed decision possible. This may mean showing non-treated rubies andtreated ones. When customers feel they've been treated honestly and fairly, you're almost certain they'll return in the future – often when they're in a position to buy a more expensive, non-enhanced gem.

0.92-ct. ruby is from Mong Hsu, Myanmar.


On the right side of the same ruby's pavilion note the large area where glass filling may have fallen out of a pit (in box). The splotch in the circle on the left side shows a glass-like filling.

Special Care Warnings
Rubies are among the hardest gemstones and are resistant to general wear and tear. But in the case of rubies with large fractures or pits that have been filled, suggest your customer clean them with a warm, sudsy cloth instead of immersion in an ultrasonic cleaner, which can loosen the filling and damage the appearance.

Advice for Sales Associates
Learn your store's policies on disclosure and returns concerning treated rubies. Your store owner or manager may want to adopt a written policy for treated gemstones of this kind that a customer can read, understand and sign.

Recommended Reading:

Gem Identification Made Easyby Antoinette Matlins, Gemstone Press, Woodstock, VT.

Gemological Institute of America's Gem Reference Guide,Gemological Institute of America, Carlsbad, CA.

American Gem Trade Association Source Directory,1997/1998 Edition (contains the Gem Enhancement Manual),American Gem Trade Association, Dallas, TX.

AGTA Gemstone Enhancements, What Your Should Know,American Gem Trade Association, Dallas, TX.

The Heat Treatment of Ruby and Sapphireby Ted Themelis, ISBN 0-9409-6510-0. Printed in United States of America.

Rubies & Sapphiresby Fred Ward, Gem Book Publishers, Bethesda MD.

Ruby and Sapphireby Richard W. Hughes, RWH Publishing, Boulder, CO.

  Legal Considerations

The trade considers heat enhancement of ruby to be permanent. But glass filling as a byproduct of that treatment isn't considered permanent. Therefore, it's wise to explain the treatment.

If you don't know whether a ruby has been treated, it may be prudent to send it to a lab for a report. State consumer laws allow customers to sue if they feel a retailer didn't disclose properly or advise them about proper care and protection. Letting them know before they buy it avoids unpleasant surprises later.

Here is what the FTC Guidelines say about gem treatments:

"It is unfair or deceptive to fail to disclose that a gemstone has been treated in any manner that is not

permanent or that creates special care requirements, and to fail to disclose that the treatment is not permanent, if such is the case. The following are examples of treatments that should be disclosed because they usually are not permanent or create special care requirements: coating, impregnation, irradiating, heating, use of nuclear bombardment, application of colored or colorless oil or epoxy-like resins, wax, plastic, or glass, surface diffusion, or dyeing. This disclosure may be made at the point of sale, except that disclosure should be made in any solicitation where the product can be purchased without viewing (e.g., direct mail catalogs, on-line services), and in the case of televised shopping programs, on the air. If special care requirements for a gemstone arise because the gemstone has been treated, it is recommended that the seller disclose the special care requirements to the purchaser."

– by Robert Weldon, G.G.

Copyright © 1999 by Bond Communications.


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