The Scientific Gemmologist

2007: I like the snowcap on a mountain analogy. Gemology is gradually morphing, but the basic tenets remains the same. Today there are new analytical instruments for gemologist (s) to analyze and interpret, at a cost, but you still need a third eye to identify unknown gemstones with basic instruments. Today consumers want simplicity. They have no time nor the ability to understand the chemical, physical and optical properites of gemstones + experience alone is not enough; you need that 'otherness', that special feel for gemstones. It's a gift from the gods, and only a few have those skills.

(via The Journal of Gemmology, Vo.IX. No.6, April 1964) G V Axon writes:

The purpose of this article is to examine the current status of gemology, to make a few comments thereon, and to report a minor research project on distinguishing man-made from natural crystals.

There seems to be a general feeling among active gemologists that gemology as a science is somehow up against a brick wall. There is a great deal of useful, interesting, and informative writing, but there is a tendency to spread the well-known techniques over a greater area instead of developing new techniques to deal with problems which currently are without solution or present considerable difficulty even to experienced and highly regarded gemologists.

Thus to a newcomer, such as this writer, there seems a tendency to emphasize the obvious, to repeat the well-known, and to avoid facing up to the fact that gemology as a science needs a new structure in its intellectual basis—perhaps, in fact, a radical decision to recognize the existence of two types of gemologists. These are, of course, the ordinary trade gemologists and those who by reason of their training, interest, and experience are, in fact, scientific gemologists whether they are in the trade or not.

Gemology, today, is rather like a snowcap on a mountain. It is the most interesting part of the mountain. It sparkles in the sun like so many diamonds. It attracts mineralogists and geologists quite apart from members of the trade and trade laboratories, and hobbyists. One can well understand its attraction. But so many of those interested in the snowcap have never bothered to understand why the snow is there, and why it stays there. They are content to play with the snow and have a good time. They are simply not interested in understanding the massive structure on which the snowcap rests.

The result is that many in gem field are walking around on intellectual stilts and might topple over at any time. They would be hard put to explain why no chromium is found in the feldspars, and why fluorite and hydroxyl ions are found in silicate minerals such as topaz and tourmaline. This is not to criticize: it is merely to point out that gems are delightful things to study and handle, and that quite apart from this the vast majority of gemologists are not engaged in any fulltime capacity in the gem field. Even those who have qualified seldom dig deeper into the intellectual basis of gemology.

Of equal importance is the fact that gemology has long been regarded as a step-child of mineralogy. The basic reason for this, of course, is that the most valuable substances used as gems are minerals, and that, without minerals, gemology and the jewelry industry would be very much the poorer.

Yet since time immemorial many of the substances used in jewelry have been man-made. Ancient civilizations have yielded very many examples of man-made gems: they have yielded only a few valuable natural gemstones. Yet because the natural gemstones are the flowers of the mineral kingdom, gemology has had to be content with playing second fiddle to mineralogy.

Plainly, this is no longer acceptable. It is not only that natural gemstones, especially the finest, are becoming increasingly rare, but that the substances used as gems are increasingly varied and increasingly difficult to distinguish. Today, gemologists, having relied probably for far too long on mineralogists, are faced with having to reconstruct the intellectual basis of their profession. The problem is basically one for the scientific gemologists.

Clearly, the first approach must be to shift the intellectual basis of gemology away from the glittering and inviting snowcap to the uninviting and less glamorous rock base. There is a need for a far more fundamental approach to the study of gemology. It should surely start with the formation of the universe, the development of the elements, the formation of the earth, and how the elements came together to form various substances known as rocks, minerals and crystals.

As some gem material is of organic origin, there should be at least some attempt to explain, as far as possible, the development of organic from inorganic life, and the organic structure of the various organic gem materials.

Today, the gemologist is faced not only with a wide variety of man-made substances used as gems, but also with an increasingly wide range of man-made crystals. Only those gemologists who have had time to look into this growing field of man-made crystals can fully appreciate its extent. Not only is there a vast variety of crystals in element and compound form, but many of these crystals may be doped by other substances for various scientific and industrial purposes. It would be almost impossible for gemologists to keep up with the developments even if they had the time. As for distinguishing the man-made from the natural crystal material, it will obviously become more rather than less acute.

Even though many of these man-grown crystals are not suitable for use as gems, the intellectual problem remains. In the United States, especially, there are thousands of amateur lapidaries who are not too willing to test their skills on anything they can put their hands on, from man-grown crystals to coprolites. Sooner or later, these curiosities find their way to the gem trade laboratory.

It was with the intention of discovering any new techniques that inquiries were made of some two dozen crystal-growing firms and scientists in the United States. The idea sprang from a comment on Carbon 14 in correspondence to this writer from J R Jones of Sydney, Australia. It was thought that if techniques were so advanced in one field, perhaps similar techniques (without destroying the material, of course) could be applied to the gem field. There must surely be some differences between natural crystals, say sixty million years old, and crystals being grown this minute in factories and laboratories.

The enquiries yielded a meager harvest. Some of the comments received are listed below mainly out of curiosity. Only in one case, dealt with later, was a basically new idea (at least, new to this writer) advanced.

1. Synthetic quartz crystals cost about twelve times as much as natural quartz.

2. Synthetic quartz crystals often have complete faces whereas natural quartz crystals often have many faces missing.

3. Synthetic crystals are much purer as a rule.

4. Synthetic production techniques often use no water, whereas natural crystals have often been produced by hydrothermal forces. Thus they contain microscopic water pockets (partially filled vacuoles). Unfortunately, analysis techniques destroy the material.

5. The majority of man-made quartz is grown in a sodium hydroxide or sodium carbonate solution. Thus the sodium content is usually higher in the synthetic.

6. Synthetics show fewer absorptions when analyzed by infra-red spectrographic methods.

7. X-ray analysis, neutron activation, and electron and neutron diffraction, were also given as possible methods.

8. X-ray diffraction topography will show a greater concentration of dark lines in the synthetic when measured against a natural crystal. Spectrographic analysis, which requires the grinding of some of the material, usually shows a greater concentration of some elements in the synthetic.

Of particular interest is the electron paramagnetic resonance spectroscopy (EPR) developed by Varian Associates, Palo Alto, California, USA. Unfortunately, the instrument costs some $30000, and the fee quoted tentatively for each spectrum was $25. Although one test may not suffice for full identification, such a test may be able to establish that a gemstone was not natural.

The basis of EPR lies in minute chemical and structural anomalies. The extremely complex instrument is an extremely sensitive, non-destructive way of detecting impurity levels in crystals. A synthetic would be relatively pure. The result is basically a graph showing straight and jagged lines, hills, and valleys, which vary according to the structural perfection and molecular structure of the material analyzed.

According to the material supplied by the company, it is now possible to use the magnetic properties of electrons (as well as of nuclei) to reveal chemical structure and bonding characteristics.

Just as nuclei have charge, mass, angular momenta and magnetic moments, so do electrons, and it is upon this that EPR depends. If the electron has not only an intrinsic magnetic moment along its own spin axis, but also one associated with its circulation in an atomic orbit, the electron will possess a total magnetic moment equal to the vector sum of these magnetic moments. The ratio of this total magnetic moment to the spin value is constant for a given atom and environment, and is called the gyromagnetic ratio or spectroscopic splitting factor for that particular electron. The fact that these ratios differ for various atoms and environments and the fact that local magnetic fields depend on the structure of matter permit the spectral separation and study according to the method of electron paramagnetic resonance spectroscopy.

It must be emphasized that not all atoms and molecules are susceptible to such study. There must be a resultant electronic magnetic moment associated with the atom or molecule under investigation; for example, effects may be observed for electrons in unfilled conduction bands, transition element ions, odd molecules and free radicals, biradicals, color centers, radiation damage sites, impurities in semi-conductors, and triplet electronic states.

The principal components of the EPR spectrometer are an electromagnet, a sweep generator, a stable microwave oscillator, a resonant cavity, a bolometer or crystal detector for demodulating the microwave power reflected from the resonant cavity (for the sample), an audio amplifier and a phase-sensitive detector, and a graphic recorder.

Possibly, this instrument has not been used much, if at all, in gemology, but the descriptions given above may plant a seed in minds better prepared in gemology than that of this writer. Certainly the idea is of great theoretical interest in the crystal field, and it seems to offer possibilities to the gemologist. It is becoming quite impossible to determine, by ordinary gemological methods, the nature of all crystals. If the synthetics and man-made can be weeded out and certified as man-made, it should then at least be easier to concentrate on determining the nature of the natural crystal material.

Hemimorphite

Chemistry: Zinc silicate
Crystal system: Orthorhombic; double termination, but of different orientation (hemimorphic); tabular and thin striated crystals; fan-shaped aggregates; massive material granular or fibrous, banded or stalactitic.
Color: Transparent to opaque; commonly banded blue or green; colorless or white, also violet, gray, yellow and brown.
Hardness: 4.5 - 5
Cleavage: Perfect: 1 direction; Fracture: brittle, conchoidal to sub-conchoidal.
Specific gravity: 3.4 – 3.5
Refractive index: 1.63 mean; 1.614 – 1.636; Biaxial positive; 0.022
Luster: Vitreous, silky to dull.
Dispersion: -
Dichroism: -
Occurrence: Secondary mineral in oxidation; oxidation zone of zinc containing ore bodies; Italy, Mexico, Namibia, Algeria.

Notes
Usually associated with smithsonite; massive may look like smithsonite, chrysocolla or turquoise; colorless (rare); crystals faceted for collectors; massive blue material cut cabochon.

Colored Stone Update

Colored stone markets are growing. The prices for top quality rubies are too expensive with supply getting difficult. Today Burma and Sri Lanka are the key sources for good quality colored stones + buying rubies and sapphires from the Burmese or Sri Lankan in their territory is not an easy task. They really know the world prices and bargain hard + they have also learned how to say No. Other colored stone species and varieties are also becoming popular. The prices for top quality Colombian emerald have increased more than 25%. Fancy sapphires are popular and selling well. Amethyst, citrine, garnet, tourmaline, topaz, ziron, feldspar have all become popular choices for regular markets + television and internet-based retailers have also helped to promote colored stones. They have made a significant impact, because they not only educate consumers by expanding the gemological vocabulary beyond the mainstream colored stones but also on pricing. Consumers have now become familiar with less known colored stones such as sphene, sphalerite, Paraiba-type tourmalines, zircon, peridot, spinel and much more + new treatments, synthetics and imitations. Unique designers have also adapted to the changing trends promoting colored stones. Consumers are gradually becoming like 'little Buddhas'.

DTC Ombudsman Starts Cleansing Role

Chaim Even-Zohar writes about the new supplier of choice methodology + the role of DTC Key Account Managers and their periodic reviews about their clients + Dermot Gleesson effect + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp

Are You Looking At Prices or Art?

Eileen Kinsella writes about the state of mind of the collectors and their ability (or inability) to look at a work, appreciate it, and evaluate it in and of itself + other viewspoints @ http://artnews.com/issues/article.asp?art_id=2268

Again there are similarities between pricing of gemstones and art. Both are subjective concepts. A piece of art or gem always have nice stories with them + they are have their special beauty. You need a third eye to see through, appreciate and evaluate. You also need expertise, meaning you need to understand how gems or art are bought and sold. If you don't have the product knowledge or don't want to take the time to learn, then you need an expert that you trust to make the judgment for you. I think most of today's buyers are collectors with a passion for gems or art and want to know everything they can about them. Some may even become too addicted; they would never part with these stones or art at any price.

Two Tricky Items

2007: I have gone through a similar situation during the course of my work, and I believe gemstones will continue to teach us one way or the other.

(via The Journal of Gemmology, Vol.IX, No.9, January 1965) G V Axon writes:

The pleasure one gets from guessing an identification and then proving it to be correct is always to be offset by the tendency to read the various gem instruments incorrectly with the guess uppermost in mind. Two stones recently gave the author a rather sharp lesson.

The first stone, about half-a-carat, was bright green, and with ‘horse-tail’ inclusions. The stone appeared pink with red flashes under the ordinary color filter, and even in ordinary light without the filter appeared to give off red flashes. The second stone, of some 22 carats, was quite a lively brown.

The first guess was demantoid garnet. The stone turned out to be chrome sphene. The second guess was heat treated amethyst. The stone was golden calcite. Neither chrome sphene nor golden calcite is seen frequently, the former because it is still rather rare, and the latter because it is so difficult to cut and so fragile.

Here were two very good examples of tricky looks. Of course, closer examination would have revealed that the horse-tail in chrome sphene did not appear to radiate, and that the doubling of the back facets in the calcite was apparent. The same would no doubt apply to a small clean chrome sphene examined under 10x lens.

Both stones were extremely tricky items, to say the least, for the horse-tail inclusion of demantoid has practically become its most single identification, yet here was a stone with very similar inclusions and almost identical in appearance. Thus ‘horse-tail’ inclusions will have to be watched rather more closely now.

As for golden calcite, so few specimens are to be seen that few jewelers will ever encounter them. Even so, heat treated amethyst is by now almost recognizable at sight—at least I thought it was, but after the shock of receiving a golden calcite and finding what appeared to be a heat treated amethyst, I have again learned the importance of never taking anything for granted, and of always making at least to tests, excluding the first ‘informed guess.’

Insight

A E Farn writes:

..........it has been mooted among people in the jewelry trade that there are two kinds of gemologists. The one, shall we say, the front-line troops who absorb the assaults of the gem-querying customer. The other, the support troops, who furnish the ammunition to them in the guise of theoretical and practical explanations. It is said that the late Harry Truman, when President of the United States of America, had on his desk a notice which indicated ‘the buck stops here.’ Likewise, we in the laboratory of the London Chamber of Commerce feel the same way about jewelry tests. Provided the item is jewelry in the broad sense—we should be able to furnish the answer. We are not magic, we are almost human, we have certain skills which predominate and between the useful combination of experience, skill, training, aptitude, comparison stones, notes, books and stored-up knowledge, we come to a decision on most items..........

Hauyne (Hauynite)

Chemistry: Complex sodium aluminum silicate
Crystal system: Cubic; dodecahedral or octahedral (rounded grains).
Color: Transparent to translucent; blue, white, gray, green, yellow, red.
Hardness: 6
Cleavage: Distinct: 1 direction; Fracture: brittle, conchoidal to uneven.
Specific gravity: 2.4
Refractive index: 1.496; SR (isotropic)
Luster: Vitreous to greasy.
Dispersion: -
Dichroism: -
Occurrence: Igneous rocks; under saturated lavas; Italy, Germany (Rhineland).

Notes
A constituent of lapis lazuli; sulphur-rich hauyne called ‘lazurite’; translucent and the rare type blue crystals cut for collectors; faceted, cabochon.