color correcting loupe is of german design with a crystal spherical concave lens set that allows TRUE COLOR Observation. it was made by BELOMO and has been with me for many years, though I could never find it in the market.. I got it at Nikin labs years ago , I suspect they were investigating production
Joined: Thu Feb 22, 2007 10:23 am Posts: 937 Location: NYC
CPOL wrote:
color correcting loupe is of german design with a crystal spherical concave lens set that allows TRUE COLOR Observation. it was made by BELOMO and has been with me for many years, though I could never find it in the market.. I got it at Nikin labs years ago , I suspect they were investigating production
I don't understand what a 'color correcting loupe' is. unless you meant standard gemologist and diamond grading loupe! For Color Grading or testing any gemstones. a gemologist needs a Non-reflective Surface & Neutral white Background, Daylight-equivalent Light Source (CRI preferably 90 or above + temperature of around 5500 to 6500 Kelvin ) without interference from external light sources, The gemstone should be viewed at a consistent distance typically around 10-12 inches (25-30 cm) from the light source. you can use a triplet loupe which consists of three lenses bonded together to correct for color distortion (chromatic aberration) and curvature (spherical aberration), ensuring a clear and accurate view. these are the standards. unless the loupe you mentioned have these details then it's not a standard gemological magnification.
you still didn't clarify about the tests that you have conducted for identification. and again as i just explained above, LED is not a correct light source at all.
My understanding is that Belmo makes high quality triplet loups. A triplet loupe design corrects for optical aberrations such as distortion and chromatic fringing. The glass chosen is designed not to impart and color cast. This is one reason that they are considered to be suitable for diamond graders. This is expected from all of the high quality triplet loupes. I see nothing in them that would account for a color shift in a sapphire however.
Joined: Thu Feb 22, 2007 10:23 am Posts: 937 Location: NYC
1bwana1 wrote:
My understanding is that Belmo makes high quality triplet loups. A triplet loupe design corrects for optical aberrations such as distortion and chromatic fringing. The glass chosen is designed not to impart and color cast. This is one reason that they are considered to be suitable for diamond graders. This is expected from all of the high quality triplet loupes. I see nothing in them that would account for a color shift in a sapphire however.
That's exactly my thoughts, at first because of mentioning the color shift, I thought he meant a color filter loupe like The Chelsea Filter or something similar...
In any case you see weird color changes specially in No heat Yellow Sapphires. their color stability changes when exposed to UV source or Sunlight. I have seen brownish Yellow (even with tint of greenish) sapphires
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21648 Location: San Francisco
Please describe what you define as a chameleon sapphire. Color change? Color shift?
CPOL wrote:
refractometer , polariscope, chelsea, spectrometer, darkfield for inclusion only & gravity test
cant seem to upload from my computer - suppose i need a place to save pics to online
Perhaps the pics are too large to upload smoothly. Make them smaller and it should work. If not, send them to ME and I will get them online. gemologyonline1@gmail.com
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