Identify Help Purple Crystals

Hello Dear
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I have below crystals and don’t know what are them exactly please help me identify this stone and it’s value .
They scratch agate .

They look like Amethyst to me, but Amethyst and Agate are both Quartz varieties, so would have near the same hardness.

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Thanks but I have Amethyst and it show by tester as quartz but for this crystals hardness is much more and tester show ruby Sapphire and even diamond .

The crystal shapes and color suggest amethyst. Amethyst will scratch agate because agate is microcrystalline and therefore more easily scratched than amethyst which is also quartz. Electronic testers are no substitute for the classic combined tests that can narrow down options, however such testers are attractive to persons who want one tool to do the job. Unfortunately, the diversity of natural and synthetic minerals means one tool just can’t do it.


You have some very nice sapphire there. Probably from Ceylon, Sri Lanka. One particular stone, on the upper right in the first picture shows the double terminated crystalline structure. Depending on quality of the stone, they can go from $75 - $1500 per carat. Your gem tester show sapphire, I have that same unit and have tried it on hundreds of different stones where I know what they are, it always gives a true reading (when used and calibrated properly), it is a very reliable device to use.

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Thanks for everybody .
I have calculated density and it is about 3.523 .
Weight = 7.4 Carat Volume = 2.1 Carat .
I have checked ruby and ruby and sapphire should be 3.9-4 .

Actually they are three types of stones as different densities and detect by detector.
Dark purple ones density are 3.523 and more harder can scratch on others and detect as diamond.
Light purples density are about 3.5 to 3.9 also the digital detector detect some as ruby some as spinel and some as sapphire.
This samples was brought me by a garnet miner.

I have uploaded some photos by 100X Zoom :::

Purple Saphire but it’s opaque needs to be heated.

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Hi all it looks to me like a mix of spinel.

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This is 100X zoom by microscope and some of them are like glass naturally.

Hi Saeed i trust that you are well? please go to the home page of IGS go up to the top and look for the drop down that will pop up, then look for the gem encyclopaedia, them scroll to spinel and read all the related pages that will continue to pop up at the end of every page I think there is a lot of little hints and tips that will take you threw the identification process. best regards jarryed.


Question: with your Electrical Resistance tester, did the needle pop all the way over to the right then settle over the Ruby/Sapphire band?

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Yes exactly it lock on Ruby / Sapphire range.

Thank you for your reply.

2nd question: did you personally mine these? Or did you purchase from a vendor? The reason why I am asking is if you know for certain if your vendor deals only in natural gemstones. Thanks in advance.

I purchased large amount demantoid garnet directly from a garnet miner and he given me this stones as sample.
he told ““this stones are from his mine and he told they might be spinel or something like that””"
Actually I have a lot of demantoid garnet with excellent quality.
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