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Article is by Craig Lynch with an introduction by Antoinette Matlins. All research described below was done by Lynch and Matlins was active in determining the extent of the problem among retailers and other vendors.
For thousands of years, the ruby has been considered one of the most valuable gemstones on Earth. A fine ruby (i) has everything a precious stone should have: magnificent color, excellent hardness and overall durability, outstanding brilliance, and extreme rarity. Such stones command high prices, and the finest and rarest rubies cost more than sapphires, emeralds, or the finest colorless diamonds. Today, however, an increasing number of people—both in America and abroad—are finding that the "ruby" they have purchased is not what they thought it was. In fact, they are nothing more than multiple, gravel size pieces of extremely poor quality corundum (the mineral known as "ruby" when it occurs in a lovely red color and "sapphire" when it occurs in other lovely colors including blue and yellow) held together by glass.
Some labs are now describing such stones as "composite ruby" and many have been found to contain more glass than anything else. Composite stones are not new, but these are produced in a different manner than old-fashioned composite stones, and as a result, went undetected until recently. Nonetheless, they are composites, and this must be disclosed to anyone considering the purchase of one. According to some respected international organizations, such as The World Jewellery Confederation known as CIBJO (an affiliation of organizations from 40 nations and whose mission is, among other things, to protect consumers) does not recognize composite stones as genuine gemstones. CIBJO defines composite stones as "artificial products composed of two or more, previously separate, parts or layers assembled by bonding or other artificial methods."
Such is the case with the composite rubies now appearing with alarming frequency within the jewelry marketplace. The starting material, the low-quality corundum gravel, has the chemical composition of ruby, but from the very start it is not considered a gem, and it lacks the requisite qualities of a gem: beauty, durability, rarity.
Composite ruby must be distinguished from other treatments routinely used on rubies. Rubies have been routinely enhanced by a variety of techniques for almost half a century, and are well accepted within the trade. One must assume that any ruby has been heated unless there is documentation from a respected laboratory confirming that it is entirely natural. Such stones are among the rarest of all gems today—an exceptional 8.60 carat natural ruby sold at auction for $465,000 per carat! Without such treatments, as this gem demonstrated, naturally beautiful rubies would be so scarce and costly that only the world's wealthiest would be able to afford them.
Treated rubies are priced according to their appearance after the treatment, and the type and extent of treatment used. Various heat treatments have been used for decades. In addition, there may be minor glass residues found in surface-reaching cracks. Glass-filling (or in-filling with oils) may also be used specifically to reduce the visibility of a larger crack or cracks found within an otherwise beautiful ruby; these are called "glass-filled" or "lead-glass filled" rubies. When present, these treatments are indicated on laboratory reports. But these types of treatments should not be confused with what is being done to create a "ruby" from multiple pieces of low-quality corundum, molded together with red-tinted glass.
Glass-filled rubies have been around since 2004, but these new "ruby-composites" began to enter the international market around 2006, and have been surfacing with increasing frequency in the USA since around 2008. In the first part of 2009 I checked approximately 30 locations in four states, looking for composite ruby in retail locations. My search included department stores, mall jewelers and independent fine jewelers. I found the composite rubies only in the jewelry departments of one nationwide department store. The good news is that for the most part composite ruby is not in the mainstream jewelry distribution systems in the United States. It is, however, all over the internet and in internet auctions, as well as in many cable TV jewelry auctions. I have also seen it in local live auctions in Phoenix, Arizona, and on a cruise ship in 2009. Many of these low-end jewelry outlets have not disclosed the fact that the items they are selling are in fact a mixture of red-tinted glass and low-quality corundum. That creates a big credibility problem for both the consumer and for the mainstream jewelry industry.
An additional cause for concern is the fact that these glass-composite rubies are not at all durable, especially when compared to ruby with no glass filling. Moderate heat from a jeweler’s torch will severely damage the composite ruby. Putting the ruby in a jeweler’s "pickle" will damage these composite rubies within minutes (J). I put a ruby in a glass and squeezed fresh lemon juice into the glass; after 48 hours the composite ruby was damaged (K). Any ruby piece of jewelry that is taken in for repair must be checked to see if there are indications of the stone being a composite ruby.
The good thing it that it is relatively simple to learn to detect composite ruby. Below I have provided information and photographs that will be a good start in the process of learning how to detect composite ruby. The information below is meant as a beginning point and does not include all of the techniques that can be used to identify these stones. Also be advised that this information is for identifying the composite rubies seen in the marketplace at this time (2009).
To examine and identify composite ruby you will need a good lighted loupe or a gemological microscope and a pair of tweezers if the stone is unmounted. A hand loupe alone is not sufficient because it is essential that the stone be completely lit throughout for examination. It is also important to move the light source around the stone: you will need to light the stone from the top, side and bottom and carefully observe.
There are three basic features to look for with your lighted loupe or microscope:
As the you examine the stone in question, use reflected light on a facet where the facet is lit up and the light bounces off the facet (A) and not into the stone. In this example, notice how smooth the facet surface is. This is a normal ruby.
In a composite ruby, much of the surface is crazed or fractured, and these fractures have been filled with glass (B,C).
 Exhibit B |
 Exhibit C |
In composite rubies not all of a stone’s facets may be crazed or fractured. The facets that are in the white reflected light (D) do not show much fracturing until you see the black fractures (dotted lines) near the right area of the reflected light. It is possible that in some cases the glass is so thick it has formed completely around the stone, so that there are no surface fractures visible in reflected light. However, the vast majority of composite rubies I’ve examined have shown extensive fracturing at the surface. These fracture are filled with glass.
As you examine the stone with a small flashlight and shine the light through the stone, you will sometimes see one or two types of flash effects. One is a flash of yellow, green or orange in a line across the stone (E). This line may be straight or angular.
Another type of flash effect I’ve seen is more regional, where a part or section of the stone exhibits a flash of one predominant color or a combination of colors, such as the blue, red at the top of the stone in exhibit F.
Most, but not all, of the composite rubies I have examined have contained gas bubbles. The classic look of a gas bubble is a bright sphere within a sphere. These can be tiny or large, individual or clouds of bubbles (G, H, J). Gas bubbles are in the glass and not the corundum (ruby) part of the stone. Gas bubbles do not occur “free floating” in ruby or sapphire.
 Exhibit G |
 Exhibit H |
 Exhibit J |
The illustrations below show the damage occurring to composite rubies in jeweler’s pickle of an hour and half. The damage to illustration K was visible to the naked eye within 30 seconds of immersion into the pickle. Illustration L was exposed to fresh lemon juice for 48 hours and then lightly heated with torch.
 Exhibit K |
 Exhibit L |
This brief article is an introduction to three of the easiest ways to identify composite ruby. If you suspect you have been sold a composite or leaded glass filled ruby in Arizona & were unaware of that fact, please .
(i) From gemstone.org, the website of the International Colored Gemstone Association