Post subject: Can Anyone Help with This blue stone
Posted: Sun Feb 14, 2021 11:41 am
Established Member
Joined: Sun Feb 07, 2021 4:01 pm Posts: 26
Hi First of all thanks for reading this post
Can anyone help in identifying this gemstone
i am new to gemology but very keen to learn
here is what ive got so far
Magnetism = No or my magnet is weak Specific Gravity= 2.666666 Pleochroism= None ? Spectrometer = looks like Sapphire chelsea filter reaction = where the feathers are, they turn red, the outside remains blue and in between the red feathers through the chelsea filter its also transparent. UV = red inside RI ( using digital refractometer) =1.578 - 1.650 = -0.072
Any help would be much appreciated
Attachments:
My Snapshot_11.jpg [ 67.01 KiB | Viewed 4287 times ]
File comment: close up My Snapshot_10.jpg [ 88.97 KiB | Viewed 4287 times ]
File comment: pavillion My Snapshot_9.jpg [ 38.97 KiB | Viewed 4287 times ]
My Snapshot_8.jpg [ 57.65 KiB | Viewed 4287 times ]
Post subject: Re: Can Anyone Help with This blue stone
Posted: Wed Feb 17, 2021 11:51 pm
Site Admin
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
A couple of points 1. Describe how you are determining SG. Photos and formulas, please. 2. What do you think the Chelsea Filter will help you determine? If surface reaching fractures appear red with CF, it suggests a dye or filler. 3. Pleochroism...are you using a calcite dichroscope or London dichroscope? Or just giving it a spin on a laptop? 4. Spectroscope: Are you seeing iron absorption around 450nm? Is that what you mean? 5. I find digital reflectometers (they are not refractometers) to be unreliable. I don't believe they can measure birefringence, can they? 6. Get a rare earth neodymium magnet for testing.
Post subject: Re: Can Anyone Help with This blue stone
Posted: Thu Feb 18, 2021 12:17 pm
Gold Member
Joined: Thu May 12, 2016 2:18 am Posts: 1542
rmohamm1 wrote:
Hi Magnetism = No or my magnet is weak Specific Gravity= 2.666666 Pleochroism= None ? Spectrometer = looks like Sapphire chelsea filter reaction = where the feathers are, they turn red, the outside remains blue and in between the red feathers through the chelsea filter its also transparent. UV = red inside RI ( using digital refractometer) =1.578 - 1.650 = -0.072
I am going to try and say this as nicely as possible and still make my point. I opened up this website this morning to be confronted with a full page of requests for identification from you. Each of these requests is accompanied by a list of property values that make no sense at all. This indicated a complete lack of understanding of how to perform the tests and apply the results.
Let's go through them.
Magnetism = No or my magnet is weak To use magnetism you need a magnet of a particular composition, size, and strength. The techniques used are also important. This information is available on Kirk Feral's website gemstonemagnatism.com
Specific Gravity= 2.666666 To give a SG value to 6 decimal places shows no understanding. In order to get the normal 2 decimal place you need a scale accurate to three decimal places, which I doubt you have. You also need proper equipment and techniques. The larger the stone, the more accurate SG results are likely to be. Very small stone are difficult.
Pleochroism= None ? What methods and equipment are you using for this call. Why the question mark?
Spectrometer = looks like Sapphire What about the spectra indicates sapphire? Where are the bands, widths, types?
Chelsea filter reaction = where the feathers are, they turn red, the outside remains blue and in between the red feathers through the Chelsea filter its also transparent. As described may indicate filling and or dyeing.
UV = red inside Completely not a valid description of a UV reaction. Also lacks wavelength information which is critical.
RI ( using digital refractometer) =1.578 - 1.650 = -0.072 Pretty much a nonsensical result. If valid it would indicate double refraction, with huge birefringence. It is therefore likely in direct conflict with your pleochroism result. The digital refractometers are totally useless. Get a proper optical refractometer and learn to use it.
As you can see your information provided is basically useless. The good news is that this is easily changed.
Read it, and learn to use the tools described in it. Remember a good gem Id is the result of accurate testing and a defined methodology. The best book on this I know of is the GIA Gem ID Lab Manual. You cannot buy this new. But sometimes I see them used on Ebay or Amazon. Make sure it is the latest edition.
Buy a basic set of good tools. They are not that expensive these days. Focus on getting a good loupe, refractometer, polariscope, dichroscope, Chelsea Filter, and and hand held spectroscope. These are relatively easy to learn to use, and most times will be all you need.
Realize the the difficult and most financially consequential separations these days involve synthetics and treatments. These separations are mostly dependent on magnification, and advanced spectrometry using expensive equipment, and the training in how to use them. At least in the beginning you should look at yourself like a general practitioner in medicine. You do the easy separations and diagnosis, and know when to refer the subject out to the proper specialists. In this case a fully qualified, internationally recognized gem lab.
This is the best advice I can give you at this time. Be assured there are people on this website with the knowledge and willingness to coach you through the learning process to a reasonable degree.
Users browsing this forum: No registered users and 4 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum