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Help identifying sapphire

Hello gem friends,

Relatively new to the gem world. I’ve been lurking around here as well as the internet trying to gather information on gems and I must say there’s a lot to learn. In the process of getting some identification equipment but any advanced knowledge is welcome. I came across this sapphire, labelled “Ravishing purple pink sapphire” in an estate sale that I purchased from. Trying to determine if its real or not. Here’s what I know so far:

  1. It has fluorescence under blacklight. While it’s not definitive, I guess it could eliminate other species.
  2. I tried to use a spectrometer on the stone. It looks like there’s a thin band in the red region of the spectrum but I don’t think I measured it correctly.
  3. I did a “flashlight in the dark” test and I didn’t see any color other than the stone color.

I’ve attached some pictures; if you can offer any assistance I’d appreciate it!


Hello Nick, Start with the basics. A polariscope is one the least expensive gem testing instruments and one of the most valuable. It will tell you if your stone is doubly or singly refractive. You can also get an idea of crystal structure if the stone turns out to be doubly refractive by using a glass ball to get a biaxial or uniaxial figure under the polariscope. Before I had a gem lab, I bought a book named, “Practical Gem Knowledge For the Amateur” by Charles Parsons. It’s a tall paperback, explaining crystal structure with close-ups of inclusions. There is also a valuable section about specific gravity. If you know someone who has a diamond balance scale, all you need is a beaker of water and a wire. You can get a very accurate specific gravity reading for any stone. When I had just gotten out of the goldsmith and GG programs at GIA in California, my first job was for a second generation goldsmith. He had hundreds of stones, either in papers or loose, and didn’t know what he had. I borrowed a RI scale, polariscope, and he had a balance scale. With those 3 pieces of equipment, I was able to identify most of the stones that he had. Synthetics had to be separated from natural, using another store’s microscope. Try the book; it is a great foundation for any reference library to identify gemstones. Good Luck, Caroline Percy Marcoux

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Hi Caroline,

Thank you for the suggestions. I had ordered a polariscope and refractometer a few weeks ago, both of which I should receive this week. Also, I ordered the book you recommended and will receive that in a few days. IGS is also offering a discount on their Pro-Gem certification which I’ll probably invest in as well. Looking forward to learning more about gemology, having some fun, and maybe find some treasures along the way.


Hi Nick,
The refractometer will give you a positive corundum id from other species and paste (glass) then I would research natural and synthetic inclusions. Different localities have different inclusions, different types of synthetics have different inclusions and beware some synthetics are treated to copy natural stones. I learnt this lesson to some expense…
Hard to tell much from the photos. Polishing marks? chips, scratches…poor faceting junctions?. Use a loop and note identifying surface features then interior features and inclusions and cross reference.
If you any of the providence of the stone that could be useful. Where and when was it first bought. All useful pieces of the puzzle.
The refractometer can take a bit of time to get used to but when you know how its a brilliant bit of kit.
Take your time and don’t jump to conclusions too quickly. Good luck

One of the first tests I run is a simple specific gravity test. It’s cheap and very quick and able to rule out many possibilities. Corundum has a higher density than most of the stones I regularly deal with, so if I’m expecting sapphire and it doesn’t have a specific gravity of right around 4.0, then I don’t have a sapphire.

Yes, it looks like polishing marks, pits and scratches as well as poor facet junctions. On the plus side, polish marks and pits are more likely with hard stones like corundum. The poor facet meets and bellied pavilion are what you would see from commercial cutting house cutting of years ago. Either an SG or an RI would help you…the SG only requires a gram scale ($20) and a small salad cup for water. Tare cup of water to zero, use a fine wire or a string to hold the stone. Weigh stone on bottom of cup for weight in air and suspended in the water for weight displaced in water and find SG by division. The RI is fairly easy after you’ve learned the basics and it will also tell you double vs single refraction, which pretty much will tell you whether it is corundum or not. The difficult part will be deciding whether the inclusions are natural or synthetic. Most common synthetic sapphire is flame fusion and this will have curved striae (curved lines) and there is an article on here about how to ID those. If you can’t find those and see other inclusions more likely to be natural, you may have a natural sapphire.

It’s none of my business, really, but I’m curious as to what you paid for this without knowing whether it was worth anything? Be aware that sapphire which is not of good color (brownish, too dark, etc.) or which has many inclusions isn’t worth much and the non-premium synthetics (such as flame fusion) can be had for pennies a carat. You can find bargains and bonanzas, but it is very, very unlikely compared to the likelihood of being swindled.

But if you love gems and are fascinated and entertained, then I guess that’s your payment.

Hello everyone,

I’ve received some gem testing tools and have been doing some sleuthing. This is where I am at the moment:

  1. Using the refractometer, I am confident I’ve confirmed it read ~1.76 on the index. There is birefringence which read ~ .006.
  2. Using a polariscope, I’ve also confirmed double refraction.
  3. Completed a SG test, I was able to get ~3.92. I have low confidence in this reading and will rerun it a few more times.
  4. I purchased this a part of a parcel of other stones from a pawn shop for a few hundred dollars. A note on one of the other stones had what appeared to be a date from 1975. I’m assuming that this parcel contains non-recently cut materials and has been sitting somewhere for a while. There are other stones that were labeled; and I’m testing them all for accuracy.
  5. Being a novice gem hobbyist, I’m having trouble distinguishing bubbles from negative crystals from fingerprint inclusions. I will try and view the gemstone in different ways a few more times.

Thanks all for your input. I’ll keep digging until I know what the outcome is.