I have purchased a massive collection of gemstones from an estate. I would like to have them appraised, but I know appraisals are expensive. I would like to have your suggestions as to how I should even start eating this elephant. I have all sorts of cut stones from clear, yellow, blue, red etc etc.
There are hundreds of stones in the collection which are in the tiny display pots but are NOT identified. I could do some limited testing. But my worry is - as an example - I may identify a garnet, but how do I know which type of garnet - there is a huge variation in price depending on the origin.
Hi I hope they are all natural gemstone, I did a favour for a person who bought a whole lot of gemstone from an estate, he was going to make a donation to our Gemmology centre, as he thought he had a small fortune, but when I tested them and advised that most or all were cubic zirconia or glass I did not hear from him again Anyway if you have a gemmological centre or even a Lapidary club near you this may be a good start. Although most in a lapidary club do not have the qualifications to identify. good luck
Hello SydP,
Thank you for taking the time to respond to my question. I am almost embarrased to say (and yet proud at the same time) that I am part of a lapidary group as well as rockhounding group, as well I am almost finished with my gemology course and diamond appraisal course with the Gem Society. I have most of the equipment that I need to become a professional - microscope, refractometer, dicrosope, etc etc
My intention was never to become a professional, just an amateur who went a bit too far and now is afraid. I have yet to pass the tests just because I don’t have a good handle on the difference between synthetics and genuine stones and the locations from which the genuine are mined. I can easily test them to determine if they are synthetic or genuine with my Presidium Tester
When I bought the estate collection at first I was excited, and now that emotion has changed to overwhelm and fear about making mistakes.
Any and all feedback is more than welcome. If more of you are in the same boat - please let me know as well.
the natural stone market is a minefield… I bought mine years ago and got them all mixed up… compared to what’s sold for cheap online these days, the quality is noticeable. However, some stones are abundant… eg. citrine, amethyst and other quartz stones. The lower quality pale stones are still at $10/ct… Tourmalines a abundant. Although most of my stones have appreciated 10 fold over 20 years, inflation has cheapened the dollar by that much also, so I will either break even or lose if I sell on either the wholesale or retail markets. The most valuable I will probably keep…several large aquamarine of 10 ct or more (large ones aren’t that valuable either but I rather have aquamarines that blue topaz which is abundant and cheap… still at $10/ct…as its irradiated)… I do have a pair of hot deep pink tourmalines from Pala, CA that I purchased years ago,they are large stones but I can’t remember the ct. weight without weighing them again…I would estimate 5 or more ct./ apiece, as the diameter at the girdle on these brilliant cut stones are over 1 cm…I would expect them to fetch a minimum of 3K a piece, and probably higher… but I could be overly optimistic… I did set a .8 ct Padparadscha in a ring, with a point diamond accent… that I bought years ago for 0.8K, now worth 3 to 5K…by my estimate… it’s intensely colored…in addition I do have rough material including castle dome robin’s egg turquoise without matrix… none of the rough have I any idea of value…without incorporating these stones into jewelry, there is no way to get full value… that being said, I don’t know how to price my own handmade jewelry… I have long retired from making jewelry due to neck and shoulder problems, so designing them and having the setting made would be cost prohibitive…
Bottom line is that I am just as bewildered about all of this as you are. I’ve been out of he market for 20 years and it’s wild and wooly as it’s all new to me again…
You have all of the equipment to do gem ID… but identifying sources from inclusions is extremely difficult until you gain experience… learning from photomicrographs is very hard… it should be a hands on process under the tutelage of an experienced gemologist… I did consider at one time taking the GIA courses in person… but my interest have shifted from stones to the geologic processes that formed them and the mineralogy of stones, as well as other deep earth processes, I am a member of the American Geophysical Union, with an interest in alkalic igneous petrology… stones are just fine quality mineral crystals… I’m collecting research papers instead of stones now.
Last word about synthetics… depending on what process was used to create them, synthetics do have characteristic inclusions. Synthetic diamonds can be a challenge even to the GIA, but there are methods that do not involve highly expensive equipment that will screen them… I attended the annual Goldschmidt conference of the international geochemistry society in Honolulu 2 years ago… there were 3 presentations by GIA postdocs and researchers on synthetic diamonds and sourcing colored stones… at that time they were quite alarmed about diamond fraud with synthetics… technology has advanced since then so they are able for the most part to easily separate out synthetics from real… colored stones could be traced to the region of origin and often to a specific mine by using advanced analytic techniques, including XRF and laser ablation mass spectrometry…the trace element profiles and isotope ratios of trace elements give geochemists the origin and geological setting on minerals and rocks…however, this kind of equipment is specialized and costs million of dollars…and also requires skilled labor to run… you would have to send them to a GIA lab or commercial lab that does that kind of analysis.
Good luck on your endeavors… let me know what you find…
I just realized that I made a mistake in my note above - “I can easily test them to determine if they are synthetic or genuine with my Presidium Tester” . What I meant to say “I can easily test them to determine if they are simulants or mined using my Presidium Tester” Sorry about that folks.
Wow Steven,
Thank you for that detail.
You sound like a busy man doing all sorts of interesting things and coming from a place of knowledge.
For the reasons mentioned in your note - I know that the simulants are getting better and better. This is my main concern. I have one grain of hope however, some of the invoices that I found with other items from the same estate were identified on the jars (some were identified as synthetic and others not. I also found
some
invoices, so, I think the collection is on average 20 years old.
I’m glad that you mentioned the value of the stones per carat. This is a good place to start, especially with the stones that are on the low end of the scale like you mentioned the citrine etc.
I don’t know yet if I have anything of value.
I think I will create a written inventory of the stones - just by color, carat (approx), and shape. At least this will give me some clarity and should provide a good starting point.
But taking some caution out of your note - I will not take them out of their jars because they seemed to have been grouped for a reason - possibly matching them with the intent to create a jewelry piece or set. They are also grouped into several trays - not sure why (again). Maybe I will discover the pattern.
If you have any thoughts (or guidance), please let me know.
I have a question that is rather off-topic from OP’s original post, but pertinent to one of his last posted comments. And, I’ve been looking for a place in the forum to pose this question…this is the best place I’ve yet found.
I recently acquired a few lots of small rubies from an auction (not Ebay, of course). I too am an amatuer gemologist with book training, many years of experience and some tools at my disposal. Most issues of identification are not too difficult for me. But, I wanted to ask about the term “GENUINE”. The auction listed these rubies as Very fine and Genuine, but it only took me some time with a lighted loupe to determine they were synthetic. (Most had no inclusions whatsoever. A very few have air bubbles.)
My internet searches have given me several articles giving the definitions of Natural, Genuine, and Synthetic. However, I would like further to know if the term “GENUINE” is a binding description term by professional, accredited gemologist standards.
synthetic corundum gems can be distinguished by inclusions characteristic of the process that created them. flux fusion methods use lithium molybdate, and other chemicals to lower the melting point of aluminum oxide as a flux. Often grown in platinum crucibles… they will have platinum and flux residue inclusions within them Hydrothermal corundums have a wavy growth pattern and “nail head” inclusions… the Czochralski method is line zone refining, it’s primary use is to grow crystals of silicon for semiconductors… when applied to make corundum, it will cause gas bubble inclusions and veils of crystal growth. The oldest process and the cheapest is the Verneuil method… this stone is the easiest to tell as it will have a lot of curved growth lines, gas bubbles and if grown too quickly, glass interspersed with crystalline material. This method is no longer used for synthetic gems but is for sapphire bearing in watches and other mechanical devices. The hydrothermal method is used for synthetic emeralds and is the only way to grow quartz crystals. Quartz is grown in industrial quantities for it piezoelectric properties… I’m only quoting the literature on this. I do not have practical expertise. The GIA articles on synthetics of all kinds are the best source of information.
Synthetic diamonds and another beast… the can be created by using vapor deposition in a vacuum, as diamonds are created in outer space… or by mimicking the pressure and temperature conditions of deep earth… equivalent to depths of 150 km or more…commercial diamond presses can grow a stone within 3 months, using an iron diffuse/catalyst. temperatures of about 1000 degrees C or a bit more, plus pressures of 5 gigapascals compress graphite in a press… these stones can be identified by iron inclusions and some irregular growth lines. The GIA has an excellent presentation on U tube on how they use spectrophotometry to assess diamonds and particularly colored ones. What is tougher or impossible to tell using all physical techniques are lab grown diamonds that do not use iron catalysts and only pure graphite. General Electric was the first to discover how to make diamond presses… by using pure graphite only, excluding nitrogen and using a higher temperature and a pressure of 7 gigapascals, and extending growth time to three years or longer, type 2 white diamonds were made and still are being made that cannot be distinguished from the real…commercial makers of synthetic diamonds don’t bother with the added time and expense to create artificial diamonds… an estimated 90% to 95% are used to industrial purposes and not for the gem market. The price of artificial diamonds has plummeted due to mass production for industry. A good lab created stone used to be about 2/3’s of natural…It’s gotten cheaper than that now but I can’t quote prices…
I have found that phase diagrams where different phases of minerals such as quartz and how they vary by temperature and pressure extremely useful… once you figure out how to read them which is not difficult at all, the information is invaluable…if the temperature is high enough, everything will melt… high pressure inhibit melting and result in different solid phases with different crystal structures…deep earth pressures and temperatures from whence diamonds come from change the phase of common minerals… as the pressure increases, atoms get crushed closer together and the crystal phases change into denser structures. the feldspar to garnet transition is only 70km deep…at even higher pressures, silica gets crushed into denser structures… exotic minerals such as ringwoodite, perovskite are formed out of olivine, pyroxenes, and garnet, as silica takes on a higher coordination number. Instead of 4 binding sites, silicon takes on 6…Ultra deep diamonds originate from this high pressure/temperature realm…400 km deep…these are type 2 diamonds that can contain boron as an impurity giving rise to blue diamonds. the high pressure polymorphs of silicate minerals are found only as inclusions in ultra deep diamonds…the most recent discovery was a mineral that was only theoretical, until a blue diamond from botswana was found containing cubic perovskite as an inclusion… cubic closest packing is the tightest structure that silicate minerals can be crushed into… it made a splash in the scientific community and was named “davemaoite” after the experimental physical chemist, Dave Mao at the Carnegie institute… none of the deep mantle minerals are stable at the earth’s surface… the only exception is diamond, which is in a metastable state… it will revert to graphite if heated.
If i’m overwhelming anyone, I’m just laying out a basic outline of some of the science behind minerals at high temperatures and pressures… there’s a lot more science that I need to know… even though I have a grounding in physics a
Hello Nova … you are correct that professional Gem ID and Valuation can be cost prohibitive. You don’t want to send glass or other man made stones, or highly treated stones to the GIA Lab for their Lab report and waste a lot of money. What I offer my clients, that are under similar circumstances as yourself, is what I call Screening Service. We also offer single specimen Gem ID Service. Let me contrast the two services to show the reduced cost savings of our Screening Service. Single specimen Gem ID Service costs $25 to $35 per item based on the size of the specimen (with verbal results … written results can be provided for additional fees). Screening Service costs $150 for the first hour of lab time where I test as many items as I can in that hour (Generally I can do 10 to 15 items in the first hour with all verbal results, live while you watch, ask your questions, and while you take your notes). Additional lab time can be purchased in 15 minute increments after the first hour if needed. Here are the general cost savings: If I do 10 individual Gem ID’s at $35 each, that cost would be $350. If I do 10 items in our Screening Service for $150 (one hour of lab time), that would equate to $15 per specimen (a 57% savings). These two services can save you hundreds of dollars in unnecessary GIA Lab costs. You would only send a specimen off to the GIA Lab after our Screening Service indicated that you have a real and high value specimen. Please send additional questions to: thediamondgrader@yahoo.com [Our Gem Lab is located in Las Vegas, NV – A great reason to plan a trip to Fabulous Las Vegas!!]
Your writing above is very well taken. You are describing the mathematical tessellation process of molecules or atoms at different pressures and temperatures. When a certain geometric shaped volume cannot fit the packed items with no remainder, then a fractalization occurs into another geometric shape that will accommodate the volume without a remainder. You see this in cube shaped diamond rough (formed at lower temperatures and pressures) and octahedral shaped diamond rough (formed at higher temperatures and pressures than cube shaped diamonds). Hexagonal diamond (Lonsdaleite) is also stable at lower temperatures and pressures. I discovered this tessellation/fractalization rule from many years of measurement/observation. Before I became a Professional Gemologist, I was a Certified Metrologist (Science of Measurement) for the Military. Study the works of Roger Penrose (Master of Tessellation); also study polytopes, Gosset Polytope and the Golden Ratio. I hope you found my commentary useful. Michael in Las Vegas, NV
You have a strong background in mathematics and physics… that’s exactly what is needed to study minerals of which gems are the best crystals…my problem is sorting thru many stones that were purchased many years ago… they were bought with the intent of setting them into hand fabricated jewelry… I have made several dozen pieces but still have many loose stones that are unset…I know what most of the stones are but don’t know their value…Most were bought cheaply and most are of a higher quality than what is sold on line today… but some of them like citrines are still cheap…
I do not have any synthetics as I have bought semi precious ones…
I absolutely agree with you that synthetics are getting better each year… each year, the GIA whose stated mission is to bring order into the gem market, does intense research on both natural and synthetic stones… many of the techniques they use are what university geochemical departments use: laser ablation mass spect, with isotopic analysis, XRF, synchrotron spect…these techniques are extremely expensive to run… less expensive ones involve optical absorption spectra, and UV reemission spectra… I only know the principles involved as I have not worked on any of these machines myself personally… what is reassuring to know is that the GIA is keeping up with synthetics.
That being said, there still are a few diamonds that cannot be distinguished from natural by any physical or geochemical techniques. My understanding of diamond synthetics is that they are grown in presses at pressures of 5 gigapascals and a temperature of about 1000 C, using an iron diffuser/catalyst for graphite. These stones are grown within a matter of a few months and have characteristic iron inclusions in themAn estimated 90% of lab created diamonds are used for industrial purposes… the price of these stones have plummeted as mass production for industrial diamonds has taken off due to high demand… stones that are grown at 7 gigapascals using pure graphite and grown for three years have no iron inclusions… nitrogen can be excluded to make type 2 diamonds that cannot be distinguished from real.
Genuine just means that it is “chemically Corundum” (Ruby or Sapphire). It could be MAN made or natural. THAT IS THE DISTINCTION. I have many Rubies and Sapphires, and am not sure how to classify them. Natural or LAB created, ie. lab created $10.00, Natural $10,000. The stones I have, (which are faceted) I am scared to put on the market. I do not want to sell a natural Ruby as lab created, and vice versa. If I am going to sell a stone. IT HAS TO BE WHAT I SAY IT IS, or I won’t sell it. Out of over 300 stones, I have 13 certified. It costs money to have them looked at and certified by a professional, but it is worth it. I am not advertising, but the person I use is Randy McCoy in Blowing Rock North Carolina USA. He is one of the most honest people I have ever met. He is not in the business for the money. But for the LOVE of gemology and what nature creates. Look up Doc’s Rocks to find him.
Anyway if you have a gemmological centre or even a Lapidary club near you this may be a good start. Although most in a lapidary club do not have the qualifications to identify. good luck