Chapter 4, page 6
Q & A Diamonds and Gemstones
Q. My mother was given an "Arkansas Diamond" 57 years ago. How can she tell if she has a real diamond or a crystal? Are the Arkansas diamonds valuable?
Thanks for your help!! Liz
A. Dear Liz,
You have a good question. There has been a lot of confusion over the name "Arkansas Diamond" because of two things: there are real diamonds that are found in Arkansas, and then there is inexpensive quartz crystal jewelry that is sold in tourist shops under the name "Arkansas Diamond" and "Hot Springs Diamond", which is a local name for faceted quartz crystal.
The easiest (and possibly the fastest) way for you to know if your mother has an authentic diamond or a quartz "Arkansas diamond" is to take it to a reputable jeweler and pay a small fee to get it identified. There are several non-destructive tests. One, based on optical properties, measures the indices of refraction (a function of the speed of light in the mineral). These are entirely different for quartz and diamond. The other test is a measure of the surface conductivity of the mineral. This test is done by using a small battery-powered electronic instrument with a probe that touches the stone and indicates yes or no if the stone is a diamond. Many pawn shops have this instrument to help them determine what the stones are in gold settings.
Also, you should clean the piece of jewelry and then look inside the band. Does it have a carat marking? If so, what is it? 10 or 14 carat (it will say 10 Kt or 14 Kt)? If it is set in solid gold, not gold plate or base metal, it may be a clue indicating a real diamond, because inexpensive stones are rarely set in expensive (10 Kt or 14 Kt gold) settings.
You might ask to look at the stone under a microscope or jeweler's loupe. If you see wear on the girdle (rim between the top and bottom) or crown of the stone (tiny frosted patches or numerous scratches on the edges between the flat faces, you do not have a diamond. A diamond is hard enough that nothing other than another diamond, will scratch it. Quartz is the most common of the harder minerals, but with the passage of time and normal wear, it will display some scratches and dings. If it is a diamond, it may display some small inclusions or spots. These spots may be black or look like colorless individual or patches of icicles suspended in the diamond. Quartz usually has few if any flaws, because due to the low price, the cutter looks for water clear flawless pieces .
Even if your mother did not get a real diamond given to her, she can wear the stone and really enjoy it! Arkansas diamond is not expensive (or particularly valuable dollar-wise), and many folks who visit the Hot Springs area buy some jewelry set with quartz crystal. I know that gift shops in Hot Springs and the Coleman's Rock Shops (connected with the quartz mining operations) in Hot Springs and Jessieville, sell a lot of this type of costume jewelry. One of the prettiest necklaces I ever bought for my wife was composed of hundreds of faceted quartz crystal beads.
Mike H.
Q. I would like to know how diamonds form? And why there are so few places that they are found. Eric.
A. Good question, and the answer has nothing to do with Superman squeezing a lump of coal! Synthetic, or man-made, diamonds can now be manufactured in a laboratory. The conditions by which they are formed in the lab are a simulation of the temperature and pressure conditions in the earth. To reach temperatures of 1700 to 1800 degrees C. and ultrahigh pressures of formation on the earth, we must go below 120 kilometers (about 70 miles) in depth.
There is a problem to be considered when comparing natural to man-made diamonds. We do not have geologic time (billions of years) to make them, like Mother Nature has. Diamonds have been dated by isotopic methods from inclusions of other minerals which were encapsulated in the diamond as it grew. Most age dates fall around 2.7 billion years old with several as old as 3.4 billion years and a few as young as 2.4 billion. One recent discovery that got a lot of scientists excited was the dating of one diamond as young as about 670 million years old. This is a young date for a diamond!
Before this discovery, most researchers were convinced that the processes that converted carbon in the mantle into diamond happened only during the time around the separation of the primitive crust, mantle and core -- a one time process during the evolution of the planet. Other recent discoveries in China of a deeply buried series of sedimentary rocks that underwent extreme heat and pressure and then were exposed by erosion has many people also excited. In these rocks researchers discovered many little cubes of graphite, the low temperature-low pressure stable form of carbon. But graphite does not form as cubes! So geologists think that diamond formed in these rocks when they were deeply buried and then changed to graphite during the time the rocks were being eroded.
So what do we geologists know about diamond in the earth?. It is assumed to be the stable form of carbon in the mantle at depths greater than 70 miles. Diamond crystals must reach the surface of the earth relatively rapidly through some mechanism because if they took too long they would be converted to graphite. Have you ever shook a soda pop and then popped the cap? The gas in the soda, due to the shaking, became unstable when subjected to a sudden pressure release. So it was with the mantle. After a sudden shock, a crack appeared and propagated (fancy word meaning headed toward) to the earth's surface. As the stuff that was blown into the crack in the mantle moved upwards, it brought samples from those great depths to the surface, including diamond.
The surface expression of the rock which came to the surface through this crack is a pipe. Pipes may or may not contain very much diamond, depending on what they passed through on their way to the surface. If they sampled layers or zones in the mantle rich in diamond, then they may be rich in diamond. Also, diamond is very resistant to erosion and weathering and it is heavier than most minerals. So diamonds that wash into rivers may be transported for long distances with little wear. Inferior grade diamonds, those full of flaws and fractures, will be destroyed by these processes, but gem-grade, high-quality stones will survive to be deposited as alluvial diamonds.
You ask why are diamonds so rare. Well, they are and they are not. I'll explain my rather strange-appearing answer. Diamonds have been found on every continent of the world. But commercial deposits are scarce for several reasons. You are looking for something small and very valuable. If of good quality and a gem grade, with modern mining methods you can make money mining diamonds with as little as 2 carats per 100 tons. What's this like? Well, imagine 10 dump trucks each holding 10 tons of rock came to your house and dumped it all on your front lawn. In this 100 tons of rock there is a diamond the size of a small green English pea -- and you get to sort through all the rock until you find it!!
Anyway, commercial deposits, either pipes or alluvial in origin, are present in Africa, China, Siberia, Brazil, India, Australia, the USA and have recently been discovered in Canada. The deposits in India were exhausted before 1840, several pipes in Africa are now mined out, several also in Siberia are closed, and Brazil has had insignificant production since 1880. The deposits in Australia supply about 35 % of the world's demand, Siberia about 20 %, and those in Africa the rest. Deposits in the USA have had little impact on the world market (Arkansas has produced perhaps only 25,000 carats since 1906), Colorado has just started production from several small pipes, and Canada is not scheduled to be in production until about 2005. So only a few places produce diamond.
However, something else important is going on here. DeBeers is a diamond cartel or monopoly that markets about 85% of the world's diamond. Ever see their slick ads on TV for diamond anniversary rings, bracelets, earrings, etc? They have trained our culture over the past 100 years, particularly our women, to believe that "diamonds are forever" and the most romantic of gemstones. Their marketing goal is for every woman to wear a diamond engagement ring, receive diamond jewelry, and to never ever sell or market these "symbols of love".
DeBeers biggest nightmare would be for all people to decide that diamonds really did not mean anything sentimental and to take them to the pawn shop to sell. Diamond would be worth nothing if this happened because the largest reserve of diamond in the world is not in some rock in the ground somewhere, but is in jewelry boxes and being worn by people around the world everyday! DeBeers biggest task is to keep everyone convinced that diamond is so rare and precious that you just can't live a good life without have one or more of them.
You might wish to visit your local library and look up diamond in the card file to find what books are available. An especially good one is entitled Diamond by Bruton. It contains an excellent summary of the history of the discovery of the major diamond deposits of Africa and elsewhere, much information about the physical properties of diamond, some chapters devoted to how diamonds are graded and cut, and a lot of information concerning DeBeers and their worldwide activities. Good luck on your search for knowledge!
Q. Iwant to know more about the stone "Lepidolite". Please tell me some resources. I have received one of these sontes as a gift and when I wear it around my neck close to my body,touching my skin, my chemistry seems to turn this pretty pinkish, lavender stone dark. I have learned it has a lithuim content. My local retailer tells me the specimen I have is from Pala CA. Any information will be gladly received. thanks. Pkaysherb@aol.com Pk Allen Midwest MI
A. Dear Pk Allen,
Lepidolite is a pink to rose-red mica which does contain essential lithium. The name comes from the Greek word for scale, as it usually occurs in fine-grained scaley masses. I suspect the reason that the stone is turning darker is because as you wear it next to your skin, the stone is absorbing oils from your skin. This is not a bad thing as a porous stone needs to have something to fill the tiny holes. Pearls and opal stones also benefit from being in contact with the skin. Pearls will absorb skin oil which will deepen their sheen and "pearlescence" and opals will not lose their internal moisture and dry out if coated by skin oils. So wear your stone and enjoy it. There's nothing magical about it, but the stone actually takes on a little of the owner! Lepidolite is a source of lithium and is often present in tourmaline-bearing deposits; tourmaline contains lithium also. Deposits of this mineral are known from southwestern Maine, from Middlesex County, Connecticut, and from San Diego County, California. Overseas it comes from the Ural Mountains, Czech Republic, Isle of Elba, and Malagasy State (formerly Madagascar).
Q. My daughter and I will be visiting Crater of Diamonds State Park, and would like to get an idea of how to hunt for diamonds.
A. Contact the Arkansas Geological Commission at 501-296-1877 and request a copy of the free brochure titled "Finding Diamonds in Arkansas!" be mailed to you. Be certain to bring plenty of fluids to drink and wear loose-fitting light colored clothing. Also, use a good sunscreen and take a wide brimmed straw hat. The area to hunt has no shade.
Q. How does one tell the difference in a genuine star sapphire and one thats lab created?
I can only assume that the stone is already cut and polished as a cabochon. We must consider several things. What's the color? If it is black or dark gray, then it is more than likely a natural stone. Almost all the synthetic star sapphires that were produced were blue. Is the star very very sharp and well defined or more broad-rayed with a "spot of light" in the center? If it is more broad-rayed (the legs of the star have some width and diffuse out into the stone), then it is probably a natural stone. Does it show growth banding in a hexagonal shape? If it does, then it is probably natural. Is the color very uniform across the face of the stone? If it is, it is probably synthetic. Is someone offering the stone for a seemingly low price? Then it is probably synthetic. If the stone is mounted in a setting, is it mounted in 14 karat gold or gold plate or fill? If in plate or fill, it certainly was considered a synthetic by the previous owner.
Of course, there are exceptions to these generalities, and they are high quality natural stones. But most folks will never see one of these stones, since when cut, they sell for $10,000 to $30,000 per carat or more if multicarat in weight.
When in doubt, contact a local experienced jeweler, preferably one who has a gemologist certificate from the Gemological Institute of America (GIA). This individual is qualified to make a professional examination and appraisal of cut or faceted stones. Keep in mind what an appraisal actually is. An example is a large cut star ruby which I recently saw. It appraised at $1.3 million, but sold for $350,000. Why? An appraisal tells an insurance company what it would cost to find another comparable (size, cut, quality) stone at full retail price on the open market, but the selling price is what the stone will actually bring on the open market. Jewelry and stones have a very large markup as they pass from the miner to the cutter to the mass marketer to the wholesaler and finally to the retailer. If you have doubts after having an experienced jeweler appraise the stone (by the way, you will have to pay for this), you may wish to contact the GIA to obtain a list of gemologists who are qualified to do gemstone evaluation in your area.
Q. A few years ago I visited the Diamond mine "state park". I was told that thereare some geological hints to the presence of diamonds in a particular part of the mine. The person told me to look for a few other minerals that are usually present with diamonds as a way to help me decide where to dig. I dont remember what they were. Do you know of any way to decide the best place to dig based on the minerals or things present... or was this just a way for the park people to give me "hope"? Thanks, Karen
A. If you are screening and get a lot of spinel (opaque black shiny grains) or pink garnet, then you would be in an area that had an unusually large concentration of heavy minerals. Since diamond is a heavy mineral, then your odds of finding one would be much better. How do you find such a spot? Look carefully at the general slope of the ground to find a place where the slope changes from a relatively steeper gradient to more gentle. At that break, small alluvial fans of heavy minerals will be deposited. Dig your material for screening from the upper end of the alluvial fan.
Q. can you advise on the type of soap to clean micro-diamonds so they can be collected by a grease roller? We have tried but they are very dirty and will not stick to grease. Hi from the NWT .
A. Sorry, you have got me on this question. This sounds very peculiar for several reasons. Granted, I have read of a few diamonds that would not stick to grease, but most of the time this problem has to do with the inability of the machinery operator to maintain the proper temperature of the grease on the grease table. I have a friend who knows more particulars about the type of grease and the operating temperature range. I will check with him (he's out of the office today and tomorrow) and will get back to you.
The real peculiar part of this entire question is that you state that the diamonds are real dirty. I have never seen a dirty diamond. All the stones I have seen, both alluvial and produced from primary sources, have been clean and lustrous and came from the ground (in the case of alluvial stones) or from the plant separator in that condition. The few stones that I have heard about that would not stick to a grease table had a coating of some type of mineral on their exterior and required a pre-treatment in a strong acid or base to remove the coating. I do not know of any soap that would remove the coating mineral. I can only think that perhaps your diamonds are coated with a secondary mineral or fall into the category of the type I just described. It would be critical to know which is the situation and especially what the coating is composed of so as to know how to remove it.
How do you know the stones you are working with are diamond? Have you had someone from industry look at them for you. Most jewelers could not identify a raw diamond if they had to, since they normally work with cut stones only.
Ch 4, page 6
AskMikey@rockhoundingAR.com revised September 1998
©Rockhounding Arkansas 1998 http://rockhoundingAR.com