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My names are Lameck James Thole. I\’m from Zambia and I\’m a gemstone cutter since 1989. I\’m currently working as Head of dept in a training school for gemstone cutters. I am hoping to learn how to value rough gemstones, and probably marketing strategies for gemstone, both processed and raw. I\’m further open to learn new trends in the sector and also open to interact with those on this platform who may wish to seek business from Zambia.

Hallo Lameck James Thole,
Ich komme aus der Schweiz und ich habe Freunde in Tansania, welche im Edelsteingeschäft tätig sind. Welche Edelsteine schleift ihr? Sind diese aus Sambia?

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Valuing gemstone rough involves a number of factors. First the species. For example, sapphire is, of course, more valuable than amethyst. Then there is color. You will probably have the most trouble with this factor, since the ultimate color of a cut gemstone is often difficult to establish from the appearance of the rough. To do the best job, you will need some color reference. You could use sample stones, but you would need a lot of those to cover all the colors of all the species. The “World of Color” sample book from Gemworld International is one accessible color reference and there are a few others, such as the GemEWizard samples that are on line. Beyond species and color, there is transparency and zoning with facetable gems and freedom from inclusions, or clarity. Regarding the particular piece of gem rough, the better it is shaped for recovery, the more valuable it is, all other factors being equal. As a cutter, you are in a good position to estimate this. Then, of course, there is the carat weight.

As far as the species, your gemology training gets you there. There are numerous books on this subject and you merely need to become conversant with the various gem instruments and to know when the ID is beyond them and the stone must be sent to an advanced lab. As I indicated, you must judge the color against a color reference under standard lighting and this is less definite for rough than cut stones, but we try our best. The weight is easy on a scale and we estimate from our knowledge as cutters what the yield will be. A wonky shaped piece of rough that weighs a gram but will only yield half a carat is obviously worth much less than one that yields a carat or even more from a gram. If you have a good microscope with decent lighting and, in some cases, an immersion fluid, you will see the relevant inclusions and can rate the rough as flawless, lightly included, etc. If the inclusions will cut out without much weight loss they are inconsequential, but if they are central, not so much. As you know, some gem materials (such as emeralds) are almost always included, whereas others, like morganite and tourmaline, are often found without appreciable inclusions. A few materials, like demantoid, actually gain value when characteristic inclusions are present (horsetails). Perhaps all of this is elementary to you already. Price guides, while they are for cut stones, can be helpful in establishing value for rough with a good deal of extrapolation. This is what we all do when we buy rough for cutting, right? You must also keep a good finger on the pulse of the market to assure yourself that the valuations you find in the books are actually current and accurate for the market…sometimes they are not. I hope this helps…ask more specific questions if you have them. I will leave the issue of marketing for now, as this is a very complex subject and depends a lot on what you are selling, how much of it, whether it is loose or set, wholesale or retail and in country or internationally, on line or in store or at exhibitions…if we knew more about what kind of material you are going to market in what situation(s), maybe some here could help.

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Replying to hear what kinds of rough you may have available, I’m in USA.