Gemstone treatments can enhance a stone’s beauty. But can you detect them and how do you disclose them? Learn about the most common techniques.
Gemstones that were mined in the USA
Beryllium diffusion typically brightens the color of ruby or sapphire, making a stone more yellow, orange, or red, depending on the original color. Because the color change can go all the way through the stone, the treatment is more difficult to identify than traditional diffusion, which is an easily-detected surface treatment. When beryllium diffusion was first introduced to the market in 2001, uncertainty about disclosure created a controversy that led to a sharp drop in prices for the diffused stones. Today, beryllium-diffused corundum sells for a fraction of the price of its natural or heated counterparts.
This slim paperback book is a real addition to the book collections of the working jeweler, the jewelry shop owner, the gemologist and interestingly also to your customer, the general public. Wow! It is a compilation of straightforward information on how to take care of gems and jewelry and covers most of the stones in general trade use. At 32 pages it is modest indeed (as too is the price: $ 9.95) but every page is well laid out, visually interesting, concise, accurate, easy to read and find information and best of all has lovely rich color photographs.
Since the discovery that the principle of electrochemical displacement of metals can be used effectively and easily to induce inclusions in snakeskin agate, I have tried the method on several of the other gemstone varieties and have found that some respond with interesting and pleasing results. These are coconut agate, Brazil carnelian and troyite. Besides these, several other agates have responded well to the process.
Dendrites, moss, plume and similar inclusions have added interest
and value to gemstone for about as long as man has been aware of the
beauty and gem potential of such “rock”. But apparently up to now,
man has been dependent on inclusions formed in nature. The process
by which they developed in nature has been only vaguely understood
and thought to require long periods of time, even in the geological
concept of time. Any means, therefore, of inducing the formation of
inclusions in gemstone is automatically of more than transitory
interest.
Tin inclusions can be induced in agate and other gemstone varieties in much the same way as with copper. Just as copper inclusions are made from copper chloride, so tin inclusions are made from tin chloride. Copper chloride imparts green and finally blue-green color to the agates, but tin chloride is colorless unless it happens to have some native color of its own. Furthermore, agate with induced tin inclusions does not lend itself to complementary color variations like the copper included agate does. It seems that, with few exceptions, slabs that have been impregnated with tin chloride will not absorb additional chemicals in solution.
Can the colored stone industry choose a standard light source from the multitude on the market?
When the first warnings about color enhancement of golden South Sea pearls came out five years ago, fear struck the South Sea pearl industry. Some of the new enhancement methods for golden pearls were nearly undetectable, leaving dealers and retailers guessing how many pearls on the market were treated and wondering whether golden pearls were going to be the gem world’s next disclosure scandal.
A summary of the most common treatment techniques used on diamonds, how they are identified by trained gemologists, and what potential problems they present to manufacturers, retailers, and bench jewelers.
Foreign affairs – A well-known European dealer sells a 2.5-carat Möng Hsu ruby to a major jeweler in Europe. This jeweler then sells the stone to a Japanese client through their Japanese subsidiary. The client now takes the stone to a gemological lab, which issues a report stating that the gem’s fractures are filled with a foreign substance. Now the fun really starts.
Historically gem possession has been reserved for wealthy, royalty, or high religious leaders. It has always been human nature to want what others possess, so imitation gems have been common for some 4,500 years, in the form of glass, plastic, composites, and treated gems. It is not against the law to imitate, as long as the true identification is given. It is only fraud when imitations, natural or synthetic, are passed off as a more valuable gem at an inflated price.
Which is the best to buy: natural, enhanced, imitation, artificial or synthetic gems? The answer depends on how you plan to use it. Natural gemstones have not had anything done to them that changes their color.
Many gemstone owners enjoy wearing their treasures. Few things can ruin that enjoyment faster than the discovery of damage such as scratches, chips, or discoloration. Unfortunately, some damage is permanent. The good news is that proper cleaning and care prevents most gemstone damage.
The most important detail in the preparation of gemstone for chemical coloration is that it be clean. Oil and grease, especially, must be entirely removed. I have found it practical to keep a bucket of detergent solution (ordinarily laundry detergent) standing beside the slab saw. Two or three cups full of detergent powder in about four gallons of water (in a five gallon bucket) is adequate. As the slabs come from the saw, they are dropped carefully into the bucket and allowed to accumulate there.
At first consideration, it might seem poor organization to include browns and yellows in the same chapter. However, I do this because in some instances the same process imparts brown hues to some gemstone varieties and yellow to others. Admittedly, brown may not be a favorite gemstone color in nature among rockhounds and lapidaries, but the browns imparted by some of these processes to at least some of the gemstone varieties I have been using are attractive in cabochons made from them.
The use of cobalt compounds to impart blue hues to glass, glazes and enamels has been known for centuries. “Cobalt blue” glass is familiar to just about everyone. It seemed logical that cobalt compounds could be useful to impart color to gemstone and this has proven to be true. Several cobalt processes follow.
Various and attractive shades of blue can be induced in gemstone by the use of copper compounds. This is perfectly logical, considering that several of our blue gemstone or mineral species owe their color to the presence of copper compounds. Familiar examples of these are malachite, chrysocolla, turquoise and azurite.
The prime requisite for coloration of gemstone is that it be porous . That is to say there must be spaces or vacancies into which the coloring chemical, in solution, can penetrate deeply in order to impart the desired color. These spaces are usually spoken of as “pores”, but from what I have been able to observe, they are not pores in the sense of parallel tubes. Rather, they are.
There are several reactions well known to chemists, involving iron compounds and prussiate compounds (ferrocyanides and ferricyanides) that yield characteristic blue precipitates. All are applicable to chemical coloration of gemstone, but since they do not differ significantly for our purposes, only one is included in this book. It involves a reaction between potassium ferricyanide and ferrous sulfate, producing a blue precipitate known as “Turnbulls Blue”.
There are only a few inorganic processes, in my experience at least, that will impart pinks or reds to gemstone. These involve primarily four metals – cobalt, iron, mercury and silver. We already know cobalt can induce blue, purple, amethyst, etc. and incidentally pink in gemstone. There are also two additional cobalt processes that impart pink or lavender, primarily or exclusively. Several iron compounds are red or reddish, common rust being a familiar example and at least one of these is useful in coloring gemstone. The same is true of mercury. And there are two red-silver compounds that are adaptable to coloring gemstone.
This book is the culmination of some twenty-five years of personally supported research on the use of inorganic chemicals to induce color and inclusions in gemstone. Prior attempts to use dyes for gemstone colorations had proved very disappointing. The fact that native color in gemstone is derived from the presence of compounds of certain metals as inorganic components (impurities) of the gemstone suggested that the inorganic salts of these metals might serve well to induce color where color is lacking or needs enhancing.
There are only two ways that I know of to induce black into gemstone. One of these involves carbon while the other is silver. Theoretically, there should be several other methods possible. I have tested these out however, and they have proved impractical. But black is black, so multiple means of inducing it are not needed. The two presented here are different in that one, the silver, is black with a metallic sheen or luster.
It seems that everyone likes the greens in chemically colored gemstone. Probably this is because greens are almost universally pleasing to the eye. No doubt this accounts for the great popularity of naturally green gemstone such as jade, chrysoprase, emerald, malachite, etc. Fortunately, there are several processes that will impart green hues to some gemstone varieties. Some of these are bluish-green and are included here rather than among The Blues…
Fluorescence is the emission of visible light from a substance under the stimulation of radiation of a shorter wavelength. It may be stimulated by (visible) light but most useful are blue light, short wave ultra-violet (UV) light, long wave UV and x-rays. Daylight contains some ultraviolet light and some artificial light sources (i.e. photoflood lamps) put out a considerable amount of UV light. An example of the effects of such light is blue fluorescing diamonds. Diamonds which fluoresce blue in UV light may have a yellow tint to them in UV free white light which is cancelled by the blue fluorescence in (daylight) conditions.
Ever since childhood, I’ve been fascinated by rocks and gems. I started cutting cabs more than 40 years ago, and have been faceting colored stones for about 30 years. I do precision cutting of colored gems these days, and that…
I’m hoping this series of articles will save some of you time, money, and embarrassment by discussing some of the common bench procedures that can easily lead to damage of colored stones – and how to avoid it. Some of…
I’m hoping this series of articles will save some of you time, money, and embarrassment by discussing some of the common bench procedures that can easily lead to damage of colored stones – and how to avoid it. Some of…
This compact self-contained screening device is designed to allow parcels of polished stones to be quickly analyzed to determine if they contain potential HPHT synthetics. PhosView cannot be used to screen for CVD synthetics simulants or any natural diamond treatments….
The mythical properties and symbolic potency attributed to jade (celestial stone) are stronger than those linked to almost any other stone. Whether it comes in deep green, shimmering white or enchanting violet, jade has for millennia been the focus of…
GIA recently released a video that provides an overview of lead glass-filled rubies and explains why it has begun to call them a “manufactured product” on reports. The video, which was created to educate the trade and public, also covers how to identify lead glass-filled rubies with a microscope and how to care for them. This article offers an in-depth understanding of this material.
Since the beginning of time, man has sought to improve upon nature. Pearls are no exception. The majority of today’s cultured pearls have undergone some form of processing or treatment after their removal from the mollusk. The only way to confidently buy in the wholesale arena is to learn what to look for and what to beware of.
An old lapidary taught me an excellent trick for sealing cracks in gemstones. Some gems are inherently unstable. If a client of mine wants one of these gems for inlay, or to be cut or set, I will often use this technique – with full disclosure, of course – to make the stone suitable for use in these applications. Also, with the growing trend of repurposing old jewelry, I am seeing more sentimental gems coming across my counter that require repair rather than replacement. Enter the epoxy technique.
The treatment and enhancement of gemstones has existed for centuries. Some enhancements improve on nature slightly, are undetectable, and they are permanent; this provides the gem market with a larger supply of beautiful gemstones. Other treatments produce dramatic changes in the gemstone; the irradiation and heating of colorless topaz that permanently transforms it into blue topaz is an excellent example. A few treatments are less stable and should be avoided by the knowledgeable buyer..
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