Over twenty-five years ago, a new treatment of gemstones was uncovered in the market that would impact the industry indefinitely. This process became known as glass filling.
The original focus was on corundum, specifically ruby, and would take un-sellable material and fill it with borax and silica to enhance the quality. This mixture when heated, turned to glass. No longer was this undesirable material discarded, instead, it opened new avenues for affordable treated genuine material.
However, as experiments continued into the early 2000s, glass filling took on a new composition. Instead of borax, lead was introduced into the glass filling. In GIA’s article in the Winter 2009 edition of Gems & Gemology, Russel Shor and Robert Weldon stated that adding lead increased the ability to mask fractures and cavities more efficiently due to its high refractive index, creating a deeper red ruby that was more transparent (G&G 2009 p. 254).
As lead-glass filling became a more common practice, developers began to create “Franken-rubies” instead of enhanced genuine stones. Stones became more concentrated with lead-glass than actual corundum, making costs at the wholesale level extremely cheap.
“Ruby” jewelry began to flood the market at unimaginably low prices while genuine material was at an all time high. Lead-glass brought forth an issue that without disclosure, would create problems in the market for jewelers and customers alike.
Unscrupulous dealers began selling lead glass without the necessary disclosure. Customers believed they got a great deal on a ruby, and jewelers would proceed in caring for the stone as if it was genuine. As a result, rubies were turning white or “spider-veining” due to heat during prong re-tipping, cleaning chemicals, or ultrasonic that would normally be safe for genuine rubies.
Another specific market targeted were soldiers returning from overseas. Believing they were buying rubies at exceptional deals, they were in fact purchasing lead-glass. Upon returning home, they would take these stones to their local jewelers and experience the same results.
Action needed to be taken to help both the jewelers and customers. As more and more found their way onto the market, gemologists became the front lines of disclosure. Fortunately, these stones are relatively easy to detect through thorough examination. All they needed was to tell jewelers what to look for.
Under magnification lead glass rubies will display noticeable gas bubbles. This is the first and most notorious sign of lead-glass filling. Also under magnification, a blue sheen can be seen which is unique to this treatment. Finally, the material will have a vibrant look while also having a “cloudy” look in the center of the stone, another sign of filling with lead-glass.
It should be noted that these treated rubies are still increasingly available on the market for consumers to purchase. While there are reputable internet companies as well as stores in cruise ships and fancy resorts, we have noticed a sizable amount of material comes from these areas. Buying from these destination stores with only one chance to buy, “super closeouts” or deals that are “too good to be true,” often lead to these purchases. A good rule to follow when questioning a transaction from these specific types of deals: the price will always be your answer.
Jewelers need to be aware that the stone can never remain in the mounting while retipping prongs or be cleaned using the steamer. Tell your customers they can’t use an at home ultrasonic and only warm, soapy water is recommended.
Being a vast and daunting industry with varying trends and material, it can be difficult to keep up. Having a dealer you can trust, who cares about their client relationships and is forthcoming, is crucial to navigating this industry. Knowing this material exists and its required maintenance allows lead-glass ruby to be an affordable alternative for customers.
Konrad Darling is the sales and marketing director for Darling Imports, a color gemstone wholesaler offering genuine and synthetics as well as lapidary services and stone identification. For more information contact Darling Imports at 800-282-8436 or www.darlingimports.com.