I agree as far as having stones professionally certed. If one has hundreds it’s extremely imposdible from a cost perspective. I have this problem. I’ve collected for so many years know the countries and sometimes the actual mines but would like to sell them but dont have certificates on them. However, if i did i would guarantee a refund to the buyer if they werent what I said they were.
do not mistake mythology for real facts. knowledge of mineralogy is fundamental in understanding gemstones… only a few gems stones are non conductors of heat that will seemingly warm up quickly to the touch… diamonds are one, organic materials, including pearls and amber are others,
Breath testing is of little use because it depends more on the relative humidity in the ambient air more than any other factor… an ice cold stone from the refrigerator will lose water on the surface in warm dry air much faster than in cool humid moist air…
This makes breath testing and subjective hand warmth testing virtually useless.
Nice to see you here, dispensing your treasure trove of vast wisdom… This is Steve from the Ganoskin community website… I just joined this website and have decided to upgrade to the professional… I could use more education in this area… I have a hoard of unset stones that I will need to get rid of, as I downsize… learning more about gemstone evaluation and valuation before selling them off is exactly what I need to know… the market still is pretty wild and wooly comparing it to the days decades ago when I bought my hoard.
could not agree with this anymore… knowing chemistry, mineralogy with the all of the physical and optical properties associated with crystals is only the first step.
how can you do non destructive chemical testing on a gemstone?
buy only from a reputable source even if it costs more… reputable dealers should have a refund policy. Unless you are an expert wholesaler, who buys in bulk directly from a mine, stay away from online auction markets like eBay or Amazon… synthetic stones should all be clearly labeled lab created or the equivalent… terms like eco-friendly are ambiguous. Expensive stones (5K and above) should come with certificates of authenticity… lab created diamonds start with a seed and are pressure cooked at 800 to 1000 degrees C and at a minimum pressure of 3.5 gigapascals (over 500,000 psi)… the process takes several years to grow large diamonds and at least one or two for a smaller one… These pressure/temperature conditions are nearly identical those in the deep continental crust/mantle transition zone, at a depth of 150-200km…maintaining such extreme pressure temperature conditions for a couple of years is expensive and dangerous… the presses that make them consume huge amounts of electricity and many presses are needed to make lab gown diamonds profitable. an equipment failure would result in a powerful explosion…labs require blast shielding, as such, lab created diamonds are expensive… a good estimate is roughly 2/3 of natural… deep diamonds come from depths at or below the 440-660 km mantle transition zone… the pressure at 660 km is 23.5 gPa or 3.4 million psi… and a temperature of 2000 C… conditions that are beyond the reach of diamond presses for/r lab grown diamonds…blue diamonds are all deep diamonds, and along with deep origin colorless ones comprise only 0.02% of all natural diamonds. Lab created diamonds have dropped steeply in price as more producers have entered the manufacturing market, especially Chinese… most of the fraudulent lab created diamonds that are sold as natural originate from China. It’s become enough of a problem that it’s become a side show in the overall US/China trade negotiations… there are no physical, chemical or optical means to distinguish natural from lab created diamonds… if you buy an expensive natural one, a certificate of authenticity is necessary (not 100% safe either, as there are also forgeries, again committed by everyone… Chinese, West African, Southeast Asian markets)… if you buy a lab created one, a certificate of being lab created is also a must…
If you have a magnifying glass and a sharp mineral it’s possible to test one of the facets below the table of a gem without the scratch (if it happens) being noticeable.
The best test of authenticity as regards the Net is the price. If the gem is very cheap it’s a fake.
Optical tests are non-destructive and I advise anybody who seriously collects gemstones to invest in a basic stereo microscope with polaroid thru-light and quartz wedge. I have old Leitz and Olympus gear made in the 60’s that are excellent but now the cheaper Chinese stuff will also do the same job. A circular rotating stage is essential and it is useful to have comparison samples of both natural and synthetics.
Chemical tests are limited and also hazardous but great for cleaning some rough specimens form adhering crap!
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optical testing using plane polarized light and a rotating stage is how minerals are identified in thin section petrologically… the angle of extinction along a crystal axis tells you what the mineral is.
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How did you go? what were their findings?
I just gave my doubts about anything from India.
The collection Ive had that Im trying to sell I bought from a friend who travelled years ago, he knew the miners and the cutters. Some cutters would give him stones to sell. He also sells to many jewelers in CA.
So after looking at a lot of these ads from India I’d only purchase from someone I knew.
Ken
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ask roy john on this website how he buys rough and cut stones. He is a professional jeweler and goes to Africa to buy rough that is cuttable. He makes a living off of buying and selling stones. cultivating personal relationships with sellers takes a long time, building trust takes a long time… once trust is built, the seller will be reliable…buying “whole sale” at markets near gem producing areas in Southeast Asia does not necessarily give you a discount… they know the market value of what they are selling and sell at retail…buying online is the least reliable. Etsy in particular is not good… you are buying what the seller says it is… often the seller can’t verify what it is since they bought it from someone else for what that someone else told them it was…there’s no way to buy something of high value that is cheap. cheap means synthetic most of the time…stones that are in the 10s of kilobucks range should all come with a GIA certificate…forged certificates are now a major problem also…Brick and mortar stores charge full retail with a 100 -200% mark up to cover the cost of slow inventory turn over…yet they are the most reliable places to buy a high value gemstone or piece of jewelry.
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thanks for the good work. your contributions are helping everyone world wide, thank you… the lawsuit is an attempt to silence fraud, you should and will win. best wishes