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Paul Hlava - The Materials Known as Gemstones

The Materials Known as Gemstones*


Paul Hlava
Access to Gems and Minerals, Inc.
Albuquerque, NM


Unlike most materials, gemstones are prized for beauty first; all other properties are of secondary interest. Other materials are chosen for various applications because they are strong or weak, hard or soft, insulating or conductive, transparent or opaque, et hoc genus omne. In defining gem and gemstone, I will show that some properties, such as hardness, durability, cleavage, etc. are also considered important. These definitions also introduce properties such as rarity and high cost or intrinsic value. By discussing the BIG seven (the more precious of the gemstones – diamond, emerald, ruby, sapphire, tanzanite, opal, and pearls – or DERSTOP), I will show how arbitrary is our consideration of these other properties compared to the all important property of beauty. A brief mention of other gemstones will illustrate the many varieties of beauty desired by people.

Crystal form is a property of the “rough” gem material which, unexpectedly, often carries over into the shape of the polished gemstone. The shape of the original crystals and the desire to waste as little of this most valuable material as possible are mostly responsible for the creation of the standard round brilliant cut of the diamond, the emerald cut of the emerald, and the ovals of ruby and sapphire. I shall mention where history has also played a part in determining these gemstone shapes.

I will discuss the distinctions between natural, synthetic, and simulated gemstones. Because natural gemstones (mined from the Earth, then ground to shape and polished) are so valuable and pricey, people (some with honorable intentions and some not) have been working to make lower cost substitutes. There have been many successes. Synthetic gemstones (also known as lab-grown, “cultured”, etc.) are medium- to low-cost materials of the correct chemical composition and physical properties. Simulants may look like a particular gemstone but are inexpensive to cheap (in all ways) substitutes for the “real” thing.

I will end with general guidelines to the properties one should consider when purchasing a gemstone. The guidelines for diamonds is quite specific and considers the properties of color, clarity, cut, and carat weight (the 4 C’s of diamond buying). The guidelines for colored stones are more generalized.

*This talk was originally developed for the Albuquerque chapter of ASM International, “The Materials Information Society,” ergo the emphasis on properties.

Paul Hlava recently retired from Sandia National Laboratories in Albuquerque, New Mexico after 33 years. He worked in the electron microprobe laboratory (as staff member in charge of the lab since 1980) the entire time. Because the EMP lab is part of the Materials Characterization Department, a centralized analytical facility for Sandia, Paul got to work on a wide variety of (prosaic to exotic) materials and projects. He normally analyzed many alloys and joins (welds, brazes, solders, metal to ceramic, glass/metal seals, etc.) but also did work on high tech ceramics, low-temperature superconductors, electronic materials, phosphors, contamination, corrosion, failure analyses, nuclear waste simulants, thermal batteries, et hoc genus omne. As a result, he has written, co-authored, and/or presented over a hundred papers on a wide variety of materials.

Paul graduated from the University of New Mexico with a geology MS in 1974. At UNM he worked as a research graduate doing probe research under Klaus Keil in the Institute of Meteoritics. He worked on moon rocks, Hawaiian basalts, ultramafic rocks, meteorites, and inclusions in diamonds. Paul occasionally uses his geological and mineralogical expertise on Sandia projects but also does some personal research on minerals. He has been co-discoverer and co-author on the descriptions of several new mineral species.

Paul stays active in the area of geology, mineralogy, crystallography, and gemology. He has been president of the Albuquerque Gem and Mineral Club three times. He is the Chair for AGMC's annual show, geological/mineralogical expert for the New Mexico Facetors Guild, and often gives talks on geological/mineralogical/ crystallographic/ gemmological subjects. About twenty years ago, Paul started a side business, Access to Gems and Minerals, Inc., dealing in gemstones, jewelry, and related items. This has not only given him access to wholesale rooms full of gemstones but it has piqued his interest in the research side of this field. He has given several well-received talks on gem related subjects such as this one.

Since retirement Paul has dabbled in penny stocks. Buying low isn’t difficult it’s the selling high that takes skill.

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