After working as a consulting geologist for more than 40 years, I decided to jump into gemology as a hobby to complement my Ham radio addiction. Presentations such as this remind me of undergrad and grad courses on optical mineralogy and petrology of many years ago. You explain refraction and refractive indices very clearly. I look forward to your other videos.
Hi Starla! :) Very good video, thanks for sharing your knowledge and experience ... and answering some questions: Digital refractometers are indeed the "internal reflective meters" but unfortunately they can’t be used so easily. In case of gemmological (and Abbe) refractometers the prism and the stage are on the same level made it possible to operate with large samples. Digital refractometers have the prism much smaller and (which make it worse) located on the bottom of the conically shaped stage. The next problem is that the measurement of solid samples is sometimes a bit tricky and to get good readings you have to manipulate with the light source, the sample, the contact liquid (amount of the liquid is critical) and finally find the correct division line (sometimes you will have several of them). Automatic measurement in such environment will probably fail. But still there are available Abbe / gemmological refractometers where the division line can be observed in the ocular but the reading is presented on the LCD. DR-A1 refractometer of ATAGO is a good example. It has build-in two LED light sources, one for measurement in transmitted and the second one for reflected light.
Thank you very much for this tutorial, Starla you have explained it so well that I could understand it in the first go. I would request you to post more videos like this on the spectrometer, microscope and other instruments used for gems identification, if possible. Once again thank you very much and highly appreciated.
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
Hi Starla, great video as always. Question: I have a few blue topaz I just bought from someone I know well and for a long time. Some are registering a very clear line on the refractometer of 1.61 whilst others I can hardly define a line. Why might this be? Is size of stone a factor?
Hi Tony, My guess is the table or facet you are testing is close to the cleavage plane so it leaves an indiscernible rippled surface. One can't polish a perfectly flat facet parallel to a cleavage plane, and topaz has a perfect cleavage plane. So, if you don't have a flat facet that is well polished, one cannot get a great ri. Try doing an ri on one of the pavilion facets.
Hi Jackie, thanks for writing. I haven't seen a refractometer go off unless it has been dropped. Sometimes there is a little build up on the hemicylinder that can be polished off with cerium oxide. But otherwise, it can be the fluid that has a lower than normal ri, or....that extra glass of wine I might have from time to time...lol
Thank you so much! You are a wonderful teacher I'm learning on my own so I need help. Quick question? Can I use the same drop of liquid for next gem or do I have to change it every time. Thank you
HI Jenn Provided the liquid has not dried too much, and there are no residual crystals, then yes, you could use it again. I only really do this if I put the second stone on quite quickly, otherwise I clean between each stone.
Hello, every stone have to get polished surface to check.. How to check, somewhere on the market in Asia, rough stone's to make sure you didn't loose your money, can you help with that, please?... Which equipment is best to take with me??
@ismail adam Will do in future. I live in UK and English is not my first language. I'm very interested in subjects of gemstones, lapidary and silver/goldsmithing. Thank you for your help and I have to say your videos really stand out in front of others. All the best.
Hello Starla. I am a student and your videos are well-explained. RI for spinel is between 1.712 to 1.762. If the refractometer reads 1.74, would the deep red (slightly brownish stone) be anything other than a spinel? Is there any other method to test for a definite answer? Thank you.
Hi Anthony Most spinels really stay in the 1.712-1.72 in ri. Your 1.74 ri and colour sounds like a garnet to me. A spectrum will often separate the two with the spinel, if red, is coloured by chromium . check out the website gemlab.co.uk and look at the different spectra for the stones.
@@starlatrwc thank you very much for answer my question by the way I am stone collector if you like to share knowledge each other send me your Whatsup number if you like have a good day
This is a GIA, Gemological Institute of America, refractometer, it's about $800, you can gat one with a CZ hemicylinder from Gemological Products in Oregon for $695 and it's really good!
Thank you for answering! Great instructional video, I have couple trays of gems that Bought and figure I should get a beginners kit of some type. I know the old saying you get what you pay for ....but still ...wondering what to do (By the way I also seen kits , Gemologists' Travel/portable Lab! Gem Microscope,Chelsea Filter,Refractometer) Question: Are you familiar with the Digital models that are out there? If so what is your option of them? (Gem-n-Eye Digital Refractometer OR Presidium Electronic Refractive Index Meter II) with speaking GIA , I taking their, GIA Diamonds and Diamonds Grading . When I finish & pass there final I going to take the Colored stones and color stones grading! Basically I retired , but rocks,gem and Jewelry making setting faceted gems is fun, do not make any money but it be nice.
What are the colors of the spectrum that will opera if we pass the light inside the red natural rubies and looked inside it through the lens magnified ,in short please Ian tired of the frequent translation into Arabic .You have to know that Ian one of your closest followers.
Hi In order to test the ri you need a flat, polished surface, or at the very least a polished surface so you can even take a spot ri. So you would likely need to polish a little window into the stone as far as I know.
the ri of the contact fluid dictates the upper limit your refractometer can give. we use 1.81 or 1.76 liquids asmany stones have an ri in the upper range.
Believe her when she says that the amount of RI fluid used is critical. Too much fluid, and little knowledge, leads one to believe that they do not have the gem that they believe it to be.
![How do you KNOW what a gem is? [Refractometer Tutorial]](http://i.ytimg.com/vi/egpxFVwtNRo/mqdefault.jpg)
After working as a consulting geologist for more than 40 years, I decided to jump into gemology as a hobby to complement my Ham radio addiction. Presentations such as this remind me of undergrad and grad courses on optical mineralogy and petrology of many years ago. You explain refraction and refractive indices very clearly. I look forward to your other videos.
This is a really excellent video! I just purchased a refractometer. Your explanation of how to use it is perfect and easy to follow. Thank you!
good teacher she explains things so normal people can understand I am also teaching my self gemology
Excellent density of useful information! We need more people like this on RUclips.
Hi Starla! :) Very good video, thanks for sharing your knowledge and experience ... and answering some questions:
Digital refractometers are indeed the "internal reflective meters" but unfortunately they can’t be used so easily. In case of gemmological (and Abbe) refractometers the prism and the stage are on the same level made it possible to operate with large samples. Digital refractometers have the prism much smaller and (which make it worse) located on the bottom of the conically shaped stage. The next problem is that the measurement of solid samples is sometimes a bit tricky and to get good readings you have to manipulate with the light source, the sample, the contact liquid (amount of the liquid is critical) and finally find the correct division line (sometimes you will have several of them). Automatic measurement in such environment will probably fail. But still there are available Abbe / gemmological refractometers where the division line can be observed in the ocular but the reading is presented on the LCD. DR-A1 refractometer of ATAGO is a good example. It has build-in two LED light sources, one for measurement in transmitted and the second one for reflected light.
I am learning about the gem stones and use of basic equipment , your video is very helpful thanks ! Much appreciated
Thank you very much for this tutorial, Starla you have explained it so well that I could understand it in the first go. I would request you to post more videos like this on the spectrometer, microscope and other instruments used for gems identification, if possible. Once again thank you very much and highly appreciated.
Thanks for the helpful explanation, 💎!
Thank-you for this useful information. I am in the process of learning refraction.
بسیارعالی لطفا مطالب بیشتری بگذارید
Well you simplified it for me! 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
www.globalgemology.com/gem-refractive-index-chart.html#/. or you can google, refractive index table. Cheers
Excellent presentation
Great job Starla!
please make more videos you are a great teacher
Hi Starla, great video as always. Question: I have a few blue topaz I just bought from someone I know well and for a long time. Some are registering a very clear line on the refractometer of 1.61 whilst others I can hardly define a line. Why might this be? Is size of stone a factor?
Hi Tony, My guess is the table or facet you are testing is close to the cleavage plane so it leaves an indiscernible rippled surface. One can't polish a perfectly flat facet parallel to a cleavage plane, and topaz has a perfect cleavage plane. So, if you don't have a flat facet that is well polished, one cannot get a great ri. Try doing an ri on one of the pavilion facets.
The Refractometer is the key
Hey Starla, hope you are doing well. I really enjoy your videos. I was also wondering if a refractometer can get uncalibrated?
Hi Jackie, thanks for writing. I haven't seen a refractometer go off unless it has been dropped. Sometimes there is a little build up on the hemicylinder that can be polished off with cerium oxide. But otherwise, it can be the fluid that has a lower than normal ri, or....that extra glass of wine I might have from time to time...lol
@@starlaturner 🤣😅🤣
Thank you so much! You are a wonderful teacher I'm learning on my own so I need help. Quick question? Can I use the same drop of liquid for next gem or do I have to change it every time. Thank you
HI Jenn
Provided the liquid has not dried too much, and there are no residual crystals, then yes, you could use it again. I only really do this if I put the second stone on quite quickly, otherwise I clean between each stone.
Starla Turner thank you again. I've subscribed because you explain things so newbies can understand lol. Ty
Hello, every stone have to get polished surface to check..
How to check, somewhere on the market in Asia, rough stone's to make sure you didn't loose your money, can you help with that, please?...
Which equipment is best to take with me??
@ismail adam Will do in future. I live in UK and English is not my first language. I'm very interested in subjects of gemstones, lapidary and silver/goldsmithing.
Thank you for your help and I have to say your videos really stand out in front of others.
All the best.
wish you showed us how it looks
Hello Starla. I am a student and your videos are well-explained. RI for spinel is between 1.712 to 1.762. If the refractometer reads 1.74, would the deep red (slightly brownish stone) be anything other than a spinel? Is there any other method to test for a definite answer? Thank you.
Hi Anthony
Most spinels really stay in the 1.712-1.72 in ri. Your 1.74 ri and colour sounds like a garnet to me. A spectrum will often separate the two with the spinel, if red, is coloured by chromium . check out the website gemlab.co.uk and look at the different spectra for the stones.
Anthony Chan ï
does it work with non translucent stones like jasper or darker jades, turquoise..... ?? thank you
No
can you clean the table with some pure water, to rinse all sulphur off?
Some people use a little alcohol to clean it, just remember not to rub really hard incase there is a crystal on the semicylinder-it can scratch it.
I'm bringing her an Apple , thank you .
Hope you will be fine if I send you pictures of gemstone can you assessment which kind of gemstone
I cannot do an identification of a stone just by a picture. Sorry
@@starlatrwc thank you very much for answer my question by the way I am stone collector if you like to share knowledge each other send me your Whatsup number if you like have a good day
I haven't tested the electronic refractometers in many years, so can't comment on them.
question what model ? Wonder what the price range is? thank you
This is a GIA, Gemological Institute of America, refractometer, it's about $800, you can gat one with a CZ hemicylinder from Gemological Products in Oregon for $695 and it's really good!
Thank you for answering! Great instructional video, I have couple trays of gems that Bought and figure I should get a beginners kit of some type. I know the old saying you get what you pay for ....but still ...wondering what to do
(By the way I also seen kits , Gemologists' Travel/portable Lab! Gem Microscope,Chelsea Filter,Refractometer)
Question: Are you familiar with the Digital models that are out there? If so what is your option of them? (Gem-n-Eye Digital Refractometer OR Presidium Electronic Refractive Index Meter II) with speaking GIA , I taking their, GIA Diamonds and Diamonds Grading . When I finish & pass there
final I going to take the Colored stones and color stones grading! Basically I retired , but rocks,gem and Jewelry making setting faceted gems is fun, do not make any money but it be nice.
What are the colors of the spectrum that will opera if we pass the light inside the red natural rubies and looked inside it through the lens magnified ,in short please Ian tired of the frequent translation into Arabic .You have to know that Ian one of your closest followers.
Hi how can I check rough stones? Your video is awesome
Hi
In order to test the ri you need a flat, polished surface, or at the very least a polished surface so you can even take a spot ri. So you would likely need to polish a little window into the stone as far as I know.
Thank you dear.. what are the negative factors of the device
Can i use other liquid or oil to use that?
the ri of the contact fluid dictates the upper limit your refractometer can give. we use 1.81 or 1.76 liquids asmany stones have an ri in the upper range.
i can not buy in Colombia, can you help me please if i send you the money, i only have the gem refractometer but not the RI. thanks Javier
👍
Believe her when she says that the amount of RI fluid used is critical. Too much fluid, and little knowledge, leads one to believe that they do not have the gem that they believe it to be.
Use an electric one and avoid this...