How do you KNOW what a gem is? [Refractometer Tutorial]
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- เผยแพร่เมื่อ 11 มี.ค. 2020
- All the tips and techniques you need to be competent identifying the vast majority of gemstones using the standard gemologist's refractometer. What kind should you buy and how do you use it correctly~
[Gempro refractometer]
gemproducts.com/products
I recently inherited around 900 faceted gem stones and now have the task of identifying every stone. The stone where in protective plastics display cases but most lacked what it is. Your explanation on how to use the Refractometer is very helpful. Thank you! This takes practice and patients.
Hi Timi!~ i'm a bit jealous. 900 mystery stones is an amusing way to spend a whole lot of afternoons XD
If you don't have already, make sure you get a refractometer and the right liquid (1.81), and a polariscope (i have a video on this one too) especially. Those two tools will go a LONG way to helping you identify these mystery tools. Feel free to reach out with whatever questions you have, as you discover new information ^_^
@@GemologyforSchmucks thank you! I just got the Gem refractometer and recommended liquid about a month ago. And tested around 80 stones so far. But have question regarding small variations of topaz vers paraiba tourmalines. When I 20x loupe some of the stones i see needles that form triangles in the thousands at different lighting angles. It looks kinda like the rubies inclusions but these these stones are fluorescent blueish greenish. I’m still learning and not sure of what I’m doing. I spend hours on line looking and reading. Any feedback will be greatly appreciated. I have a 20x loupe, a scientifically microscope, RI meter with 1.81, a Diamond tester I bough on eBay for $12.34 and a UV pen that I’m not quite sure on how to use in stone identification. Lol.
@@timlee4213 My suggestion is to be systematic and make sure you know how to get a good RI reading. If you can get an accurate RI and know the full birefringence range of DR stones, you will have some POWERFUL information. For example, Topaz and tourmaline may have similar RI ranges, but Topaz has 1/2 the birefringence of tourmaline. Master the refractometer and polariscope first. AFTER that, you can move on to other tests. Don't trust the diamond tester. For now, put it in a box and put that box in another box and put that box in your closet. It is a deceiver for new gemologists ^_^
@@GemologyforSchmucks thank you! That was very helpful. I’m steadily get the hang of this, and that Diamond tester is defiantly something put off to the side.some of the larger stones that are over 20 carats are much easier to work with and I will continue to practice the very valuable advice given. Thank you very much for your guidance in this fantastic journey of gem identification, if you want, I have more than enough gems to share. And will be glad to send you stones for you to have and keep. No strings attached. And ment for your enjoyment.
@@timlee4213 I'm glad that you're enjoying the process of discovering and identifying Timi. I also appreciate your generosity. Once the borders open up etc, who knows where the world will take us, and perhaps we'll have an opportunity to talk over some of the stones you have ^_^
Mr. Nelson, thank you for your informative content. Very interesting stuff.
Thank you Stephen~
Thank you so much for this!! I always wondered how they could differentiate stones
It's magic. Also definitely science XD
Absolutely the most helpful and well explained video about refraction readings. Thank you Peter!
My pleasure, Sam. Glad you enjoyed it.
I use a GemPro Refractometer. It is excellent.
They are excellent indeed. I've heard that they have been discontinued however. I hope someone new can step into that void and continue making excellent refractometers, so that we're not just stuck buying the big names.
A good refresher video!
Thanks Rick~
So helpful! Thank you.
My pleasure~ glad to be of service.
Excellent tutorial and explanation of an important but finicky skill in the gem world .
Thank you for your high praise ~ it is indeed an important skill and instrument for the gem world. Its amazing how many people think that you can just look at a stone and know what it is with certainty, and if you dont, then you're a hack. Unscientific madness~! XD
Cheers
The test liquid looks like iodine or mecurichrome. Your channel is by far the most concise and information dense one on TH-cam. Thank you for being so helpful! 😃
Thank you James~ The liquid goes by a few names, but one of them is diiodomethane. I'm not a chemist(YET!), but I wouldn't be surprised if there is a relationship with iodine.
I looked it up for a video and found a tweaker with a Trump hat and an American flag as set dressing. Shirtless, ha described diiodomethane as "liquid cancer."
The recipe followed, I didn't. Strange planet since Covid. ✌
@@jamesbarisitz4794 It is indeed a strange planet.
Great info.
Thanks~ glad to be of service
Thank you dude. For real.
My pleasure Ian~ Its one of the small steps I can do to make the world bigger rather than smaller. Hopefully i'm getting better at it with time XD. Cheers
Refractometer spot reading remain my tricky one , and honestly I’ve seen some people taking the funniest positions on their chair just to read it.. maybe a video more detailed about spot reading for cabochon and some gems that are badly polished. Thanks
Spot reading is tough ~ many people with accreditations are still not great at it #shame. As to the badly polished stones: the refractometer can only function if the stone is polished well. It's not about skill. When a stone has an overly dull surface, the refractometer cannot take an accurate reading. Even reputable labs will say: go get a better polish on this stone, OR pay for the certificate where we'll use high-tech machines to analyze the stone. Not all labs have machines that cost as much as a house. Many labs use basic gemological equipment, and to do that, a decent polish on the stone is important. If we want to know the truth, we have to decide what we're willing to pay for the truth eh?
مرحبا ..لانني لا اجيد الانجليزية لم افهم اي شيء لكن تبدو معلومات قيمة للجميع ماعدا انا....شكرا😅😅😅😅😅😅
So would it just be a different oil to be able to get the RI reading for, say, diamond? If yes. Do you happen to know of what type of oil that would be? I do know that a diamond/ gem tester would likely be the go to for that type of thing but I am curious just for the sake of knowing.
Wow that looks slightly difficult. I like it. If you can only get a polariscope or a refractometer, which one would you get first? Is it a simple machine that can be made in a cheap way or do you really need a professional one? What about those small portable ones for honey and beer? Would they work? Thanks
The foodservice refractometers are quite different. Don't go that route, i'll say. A polariscope is excellent, but its kind of like saying left, right or center and getting a clear answer. A refractometer is like saying, "How tall are they and how high can they jump?", and getting an undeniably accurate answer.
Sir, thanks for excellent and precise information. I will be grateful if you can answer whether we can find the refractive index of opaque stones like torquoise.
Great question - as long as the polish is good, you should be able to get an RI, yes. Soft gems often lose their luster quickly, which will make reading an RI difficult.
I'm doing the GemA Foundation and refractometer is the most frustrating thing ever. I could do it really well on my tutor's one with the external wheel, but I suck at it. I'm surprised that there isn't a digital one these days :(
Keep at it and you'll get there. Is there someone who can look over your shoulder and confirm when you do it correctly/ are you using stones with known (already confirmed) RI values?
@@GemologyforSchmucks Thanks for you reply and encouragement. Unfortunately my tutor lives quite far away. I find the isotropic gems fine, but it's the anisotropic gems that are hard (I'm using the gem set that GemA gives you). Perhaps I was better with my tutor because we used bigger stones? I'll keep practising.
Hello Mr. Nelson, I hope I'm not being too much of a schmuck lol, but what does it mean when you say the "C" - axis.? Thank you for all your videos. I am studying to become a gem cutter and learning so much from you. Hello again, OK I got it. It's the longest direction between a crystal's sides before cutting a crystal. I so enjoy your videos.
Hi Delilah~ C axis is a term that we hear a lot in gem cutting and its one of the directions of crystalline growth in certain crystal systems (there are 7) I believe there is different terminology for biaxial stones technically speaking, but that is beyond my understanding. You don't need a full academic knowledge to be an effective cutter, but grasping the idea that colour changes depending on how you orient the stone facets is key.
Love your show & humor - even though l can't grasp all you said l still watched anyway its interesting 👍 l have part time hobby of buying vintage pre-owned pieces at a good price (especially) when theyr not sure what it is & l "think" l know what it is - it's like a treasure hunt - then try to figure out what it really is ? - lucky for me l have a good friend that's quite good at helping me to identify the mystery stone - 9 out of 10 that works - but if confirmation is needed beyond that ? (Rarely) then off to crystal cave to ask the owner of the store to please help i.d. "said mystery stone" - nothing is more interesting than a heading saying "unknown stone" 😁👍last time it ended up being a sm pendant of gem quality labradorite :-D l have 1 right now not sure if it's the blue aragonite lm hoping for ? - or if it's Larimar?? - seems l always have at least 1 at a time lm not sure of & searching 4 it's identity - lm so glad l found your channel ! - you take things to a whole different level ! - thank you for sharing your knowledge:-)
My Pleasure Sherry - i'm glad to be of service. You also live a life of adventure, I see :D
Super 👍👌
Thanks Prasad~
What was that red orange stone? It was absolutely beautiful. Lab created?
That is a stone called Sphalerite and it is completely natural.
I've heard that using a 589nm mono light-source provides a much more distinct measurement line. What are your thoughts on this? I ask, becuase recently I was trying to test for a tiny birefringence, and a cleaner measurement line sure would help. Thanks for all you videos - they are a tremendous help!!!
In lab conditions, yes it's effective. The ghetto option would be your phones torchlight (works, but not ideal.) There are some sodium light (589nm) filters that can accomplish this. The refractometer in this video actually came with a small filter included.
Thak you
My pleasure~!
Another great video - thank you. I'm having difficulty with small gemstones... I'm not sure where to put them on the hemicylinder. HELP! ;-) Also, for non-circular gemstones, is it better to position the table parallel or perpendicular? Thank you, Peter.
Hi Timm~ Glad you enjoy my videos. For any stones, its best to start with the lens OFF the refractometer, as that makes it easier to locate where the image of the stone is coming through in the display. Small stones make this much more important. If your model does not allow for the lens to be removed completely, then push it in to its lowest magnification position, and make sure that the stone is located in the middle of the window on the center of the hemicylinder.
When testing stones, circular or non, it is important to get an RI reading from several different facets. This is actually one of the ways we can detect when composite/trick stones are in our hands. So i usually check the table (as in table directly on the hemicylinder), and a pavilion facet or two.
Thanks for the question
@@GemologyforSchmucks Thank you, so much - that should make things sooo much easier. I never even thought about reading the pavilion cuts too. ;-)
Hi Peter, just joined your channel. Question; what would you use to verify RI on a large gemstone too big to fit on this machine and be covered with the light shield?
Howdy ~ welcome to the channel. The light shield on this model and I believe the GIA version are removable. Even large stones are checked with this method (carefully...) You just need a well polished facet/ window.
@@GemologyforSchmucks Right on brother, thank you! Enjoying the learning :)
Very interesting video. I just bought my first refractometer off ebay, very cheap price, around $120 with liquid refractometer. I bought it because I have a few gemstones I wanted to test, presumably sapphires. It took me a little bit of time to see the lines. Something i noticed is that, the sapphires I tested are within refractive range of sapphire but the birefringence is less than 0.008. Is that normal to find sapphires with lower birefringence of 0.008? Thanks!
Hello there Vantage Silver~
Congrats on the new tools. The thing about refractometers is that they rely on the stone being well polished, and the glass part of the refractometer's hemisphere being maintained. Certain hemispheres are made from glass that gets tarnished over time, and that will make it difficult to get a clear reading. If the gemstone isn't polished well, you'll get a blurry reading...
So all that is to say - if you feel that the RI of these suspected sapphires is off, you'd want to make sure that you're testing on facets that are better polished, and very clean, and you'd want to inspect your refractometer.
Otherwise .008 is the normal RI for most corundum in my experience, though it can go somewhat higher or lower within reason depending on what the trace elements colouring the stone are. Intensely coloured stones can be higher RI and faintly coloured stones lower~
Thanks for the comment.
Excellent as always..
Sooo...if you have to turn the stone to catch the second refractive index, does this mean if a rough is polished for checking on the refractometer on the single refractive 'C' axis it would show as falsely singular refractive?
Thanks very much Robert~ And yes, you're absolutely correct. If by some weird twist of fate you manage to polish a facet directly in line with the C axis, it will show as a "false" singularly refractive stone. Practically this is highly unlikely, but that is also why it's best practice to check two facets on any stone, on two completely different axes.
Thanks for answering yet another weird question, they are getting harder to come up with.
@@roberthamblett9619 😅🤣😅
Interesting
Thanks~
Hello, have a good day, is there a table for reading gemstones? For example, when examining any stone on this device and the number 1.55 or 1.6 came out, for example, is there a table that matches the numbers to know the type of stone. Thank
There are advanced machines that can automatically read the refractive index, yes. They are not cheap, and therefore not widely used. A competent user can own a device like the one shown in the video and afford it without losing their house.
And yes, there are also tables of the identification characteristics of gemstones available in a variety of books on gems and provided by gemology schools etc.
Thanks for the question.
@@GemologyforSchmucks Yes. Thanks. I mean if you know the refractive index with this device. How do I determine the type of stone? I mean, for example, I examined a stone and it showed me a refractive index of 1.6, how do I know this number for any stone! ? Is sapphire, emerald, topaz...
@@mazinalhoseny Once you have found the refractive index/RI (and birefringence if it has it) you consult the charts that you referred to, and that I mentioned were available online and in reference books. Of course RI is only one of a series of pieces of information necessary to determine the nature of the gemstone. You'll want to combine that with the other characteristics of the stone to rule out other possible gems.
With the gempro can you determine if a stone is negative or positive. I did not see the two RI’s.
That will depend entirely on the stone that you're investigating. Some stones have a smaller RI range and that will make determining optic sign much more difficult. All of the models of refractometer that I have used have a very similar scale and viewfinder size. The key difference that I have seen between the gem pro vs some of the other models is the material of the hemicylinder, which on the gem pro often reads more sharply/ sensitively. Other brands may have issues with the hemicylinder tarnishing aswell, which further makes reading the RI less clear and noticing negative/positive optic sign becomes a massive challenge. Thanks for the question~
Can you suggest me from where I can buy a monochromatic light source? I have a GIA refractometer without the light source.
Halogen lightbulbs are one of the most highly recommended. There are also sodium light filters available. That said, its not strictly necessary for general identifications. An LED or your phone's flashlight works for general identification needs. You'll know the difference between tourmaline and corundum with those.
Great vid. Often ppl use too much liquid. That can throw off your reading as well. Less is more.
Yes ~ too much liquid absolutely can. Less is more in both senses: better test and longer lasting bottle of liquid.
Hello Shamachs
Nowadays we can buy such kind of testers which can calculate RI just by putting gem inside the box. Could you please tell us the difference
Some of the hi-tech gemmo raman can do some amazing things. they're also a few tens of thousands of dollars, and a nice refractometer costs around $1,000. Technology shouldn't replace knowledge. Even those who afford the hi-tech devices should understand how the science works in my opinion.
@@GemologyforSchmucks totally agree with you but again does gem testers included RIMeters work worthwhile?
se podria poner al ESPAÑOL ESPAÑOL ESPAÑOL GRACIAS
so how would I apply that knowledge of the refraction to find out what gem it is? Is there a chart?
Yes there are charts and compiled data in books and websites. Wikipedia even has it~
The Gem Reference Guide from GIA is well compiled, as is The Handbook of Gem Identification by Liddicoat.
If you'd like a free reference, mindat.org is nicely searcheable.
Hello,
Please can you assist.about digital refractometer.its a better choice or this one is better to find aut the accurecy and result. TIA.
All the experienced gemologists that I know use this same sort of optical refractometer with refractometer liquid.
Forgive me if my question is in the dumb a*** range but is the process
used by the electronic gem tester the same as the gemologist's refractometer ?
Thanks for all you tips and techniques.
Secondly, once the divide is determined is there a scale that can be used to
identify the gem under examination ? i.e. does the level of refraction identify
the gem ?
Hi Brian, it's a great question, and one I wish more people would ask and listen to the answer of.
No. They test completely different properties. The pen type/ electronic testers typically test thermal/ electrical conductivity.
The type of refractometer in this video (the standard gemological refractometer) measures optical refraction (the manipulation of light as it enters the stone or reflects off of it.) It isn't 100% of the information that you need to determine all stones, but it narrows down the search a lot. For example, a sapphire is usually going to have a refractive index of 1.76 with some slight variance. If I test a stone that is 1.65, then I know it can't possibly be corundum/ sapphire. I have to then use another test with another tool and let the data guide me to the identity of the stone.
@@GemologyforSchmucks Many thanks. I gotta get the refractometer.
A little learning is a dangerous thing dontcha reckon ?
@@brianterence3211 A little learning is indeed dangerous, but then again, safety is boring and boredom is the real killer. so!~
Per pietre grezze più grandi che non entrano nel rifrattometro, qual è la maniera migliore per essere certi di che tipo di minerale si tratti?Grazie per la risposta. Nuovo iscritto
Welcome to the channel- a large rough stone is still fine, but there must be *a well polished facet* A several kilo boulder can be used with this refractometer, as long as the gemologist is strong, and the facet is well polished. Cheers~
Is there any type of device to measure RI of rough uncut stones ?
There are advanced machines that can do this yes, but they’re often prohibitively expensive. Even most small/medium sized labs wont have this type of equipment, as sound gemology knowledge and a few of the basic tools are usually enough for most gem materials.
Hi. I am interested to buy refractometer. What you think about digital one? Like Presidium Refractive Index Meter II?
Hi Stefan ~ Among serious gemologists, I don't know anyone who uses a digital refractometer. I'm not saying no one does, i'm just saying that im skeptical that it works. If the tool was superior, i'd expect more people to use it. That said ~ if I ever find someone with one, i'm likely to make a video of testing it out. Thanks for the comment.
@@GemologyforSchmucks In fact, I got a recommendation from a gemologist to buy that device. Since I am a goldsmith, he thinks that it is easier for me to use digital one. I asked you because I wanted a second opinion. Thanks for the reply and if you make a video about it I will be happy to watch it 🙂
Is this tool useful in differentiation between synthetic rubies sapphires etc?
Great question, and the answer is short: no. Natural and synthetic gemstones (with some minor exceptions) have all the same physical, and optical properties. To distinguish natural from synthetic, gemologists use the inclusion scenes within the stone. Trace element chemistry tested with advanced (and incredibly expensive) machinery also comes in handy, but the fastest and most reliable method begins with a loupe or microscope.
@@GemologyforSchmucks thank you so much. I am from Sri Lanka and just getting started on sapphires after inheriting fathers collection. I have sent you a DM if free do have a look
@@GemologyforSchmucks also I have a possidium 2- would that be more reliable to check the gem type based on hardness or do you recommend a refractometer?
@@Test97913 Refractometer is far more useful for coloured stones.
Can we get handouts please?
At this time I am not selling a course or educational materials. If that changes in the future, I will make sure to inform everyone.
where can i get a pro loupe, amazon is questionable !
th-cam.com/video/E0eZuYx-dW8/w-d-xo.html
th-cam.com/video/aKz_KTlQvIw/w-d-xo.html
Refactor meter can u use uncut gemestone
The refractometer requires a high polish on the stone. Some uncut gemstones have a polished and well formed crystal face because of their growing environment, so occasionally you can get a decent RI reading with these.
If you have rough and worn surfaces on gem materials... like sapphire pebbles found in rivers etc... then you can't use the refractometer with these until there is a polished, and preferably flat surface.
Is Specific gravity a good enough measure when identifying a gemstone without having to use this device?
Great question. The short answer is "NO!" :D
many new gemologists want to use specific gravity, but there are many stones that have overlapping or very close specific gravity ranges. RI is a MUCH more useful piece of data.
@@GemologyforSchmucks thank you for responding so quickly it's much appreciated and incredibly useful. I did suspect sphalerite, but wasn't sure because I've not seen one yet (just still images). It's a hell of a collectors gemstone with unparalleled brilliance!
@@aurangzebkhan5967 absolutely ~ sphalerite is super unique. The high R.I gives it that really high luster and reflection, which is part of why they can be difficult to photograph. Look forward to the day that you can see one in person. You’ll know when you see it :D
@@GemologyforSchmucks Is the colour similar to citrine ?
Or does it exist in a variety of colours ? Does it has refraction
index similar to diamond ? Thks.
@@brianterence3211 I don't feel the colour is similar to citrine, no. Much of the sphalerite I have seen is much more intense in colour, though perhaps less syrupy than citrine colour can be.... if that makes sense.
So this is just for loose gemstones?
As long as the stone has a flat facet protruding from the setting, you can use the refractometer aswell.
Hello Sri.I'm sri Lanka how mach
gemproducts.com/products
🙏👌👍
I am going to GIA soon and I'm trying to bush up knowledge before I get into classes and my god.
learning Gemology is like learning a new language and using alien technology I am so confused.
It's a wild journey at the beginning for sure, but shapes start to form in the fog if you keep at it. Take one step at a time, and then take another after that: you'll get there.
@@GemologyforSchmucks what college degree would you recommend after or before getting a GG? What could help you in the industry?
@@Hiyooma Degrees are not important. Character and burning desire are important.
@@GemologyforSchmucks thanks :)
KNOW ABOUT PURPLE PINK SPACE DIAMONDS?. THAT DIAMOND CUT LOOKS LIKE A ALEXANDRITE I GOT, 12CTS THO
That is not something that folk around here really talk about, no. I hope what you have delights your eyes.
@@GemologyforSchmucks WELL, OK
Where did you go to school?
I studied gemology (A.G. program) at AIGS in Bangkok, Thailand.
@@GemologyforSchmucks thanks for the reply. I am an aspiring gemcutter. About to cut my first sapphire today with help from a teacher. I will probably buy this machine down the line.
@@sum1799 how did the sapphire go? And did you buy the meter?
စမ်းသက်သောထိုအရာကဘာလဲ
What is a schmuck
Excellent question, and its answer will depend on who you ask. In this context, it's a word taken from Yiddish (which took it and totally decontextualized it from the German word.) In its most common usage in pop-culture in the US, it's meaning is something mildly derogatory like "dummie" and its used in the title of this channel as a nod to the book series that makes various dense topics of interest available to the average person in plain language. That's what I hope to do on this channel: share information on a dense topic in a way that is accessible to anyone who accepts that they still have things to learn. Cheers and thanks for the question.
@@GemologyforSchmucks are you not happy with being a gemologist.gemstones are my passion since I was little watching the goonies
@@cwenterprizewells1104 I am certainly happy that I became a gemologist, and its something I devote a large amount of my waking hours furthering my understanding of. This channel is one part of what I do to make the world of gemstones available to others that may have thought gemstones were out of their reach. I'm glad that you also share my passion for gems.
@@GemologyforSchmucks brother if you only knew what I have in my collection.the issue I have is someone to listen and take me seriously.and who to trust what should I do first for my protection.on major discovery
FYI we don’t call a speedometer a “speed o meter” nor is a refractometer called a “refract o meter”. As the great orator “Popeye” once said to Ms. Olive Oil you was having problems wif your e nunski ation.
There's a strong argument there. That said, I'm not an advocate of prescriptive linguistics, so i'll likely continue on stubbornly in my ways for the foreseeable future.
@@GemologyforSchmuckswell said!