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Presidium gemstone tester?

Elizabethhunts

Rough_Rock
Joined
Jun 22, 2020
Messages
96
Hi all! Im looking into investing in an at home gemstone tester i can trust to be accurate. Has anyone heard of or used the Presidium gemstone tester? Its says it can differentiate between diamond and mossainite as well as 16 common colored stones. Jts well reviewed on amazon but for almost 300$ I want to be confident in the purchase.
I apoligize in advance if this is posted in the wrong section of the forum.
 

oldminer

Ideal_Rock
Trade
Joined
Sep 3, 2000
Messages
6,392
I can't differentiate man made versus mined rubies and sapphires. It is useful, but it will not tell you enough to be sure about many stones. You have to be knowledgeable to use it correctly or you will simply fool yourself and waste $300 bucks. Professionals use a series of test equipment and few rely on such electronic test tools. They do not do the necessary job of identification, but can assist in a part of the process if you know how to use them and what to expect out of them. There is no magic black box to identify many gems.

It can't tell mined diamond from lab created, I can't tell oiled or dyed or glass filled natural gems from untreated ones. Way too many important things it can't hope to do.
 

Elizabethhunts

Rough_Rock
Joined
Jun 22, 2020
Messages
96
I can't differentiate man made versus mined rubies and sapphires. It is useful, but it will not tell you enough to be sure about many stones. You have to be knowledgeable to use it correctly or you will simply fool yourself and waste $300 bucks. Professionals use a series of test equipment and few rely on such electronic test tools. They do not do the necessary job of identification, but can assist in a part of the process if you know how to use them and what to expect out of them. There is no magic black box to identify many gems.

It can't tell mined diamond from lab created, I can't tell oiled or dyed or glass filled natural gems from untreated ones. Way too many important things it can't hope to do.
Thank you for your very detailed reply. I didnt plan to use it as an "absolute" means of identification, but as I continue to learn about gemstones I wanted to at least have something at home that can verify "yes this is corundum" and from there i can study the gemstone knowing what it is.
Even this model will only recognize 18 gemstones! If I do purchase this device, there will come times the machine wont even be able to tell me the base of what im observing.
This sort of purchase would be an "investment" or even possibly an incentive for me to pursue knowledge and experience in identification and classification of minerals and stones.
Im so used to buying loose stones from my jeweler, i trust that they are exactly what he says they are.
However while gathering metals for refining i have extracted so many loose stones from scrap gold and silver jewelry that i cant identify, i feel a bit wasteful of them all. Theyre gathering dust in a box in my closet.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,315
These gadgets get more people into more trouble than they are worth.
i am with Dave.
My staff buy them when I am away and hide them.

learn the breath test
the read through test
the lip temperature test

and when all else fails the scratch test because most of what you get will need reploishing and regrading
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
9,760
Better idea for the money to be spent on microscope or some good loupes.
Then find a website that sells lab gems for under a buck each..get atleast one of each they have around 5-6mm mosly ovals but other shapes if ovals are not available.
Then see what the have in low end naturals cheap and buy a bunch. Add some cz in different colors.
You could easily end up with 75 or so known samples for not a lot of money.
study them
 
Last edited:

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
7,393
I can't differentiate man made versus mined rubies and sapphires. It is useful, but it will not tell you enough to be sure about many stones. You have to be knowledgeable to use it correctly or you will simply fool yourself and waste $300 bucks. Professionals use a series of test equipment and few rely on such electronic test tools. They do not do the necessary job of identification, but can assist in a part of the process if you know how to use them and what to expect out of them. There is no magic black box to identify many gems.

It can't tell mined diamond from lab created, I can't tell oiled or dyed or glass filled natural gems from untreated ones. Way too many important things it can't hope to do.
Just to check, good sir... :)

When you said 'I' (at the very start and in the second paragraph) did you mean to type 'it'??
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
20,691
IMO a good loupe, a good set of calipers, a good scale, and a thorough appraisal would be a much more productive and reliable way to spend the $300 (though, granted, all of those together will cost more than $300). All those testers are mostly wasted money.
 

Bron357

Ideal_Rock
Premium
Joined
Jan 22, 2014
Messages
4,230
I have one. It is useful for telling glass (Cubic Zirconia) from anything else. It is useful for identifying quartz varieties from Corundum or Topaz.
It can not tell you if the material is natural or made in a lab.
It can not tell you if there are treatments or filling.
Of much more use is a loupe and an understanding of what internal features different gemstones have.
Often times identifying gemstones is a multi step task.
If buying jewellery I first consider the setting and quality of manufacture. Natural gems are more likely found in hallmarked metal. If set in 18kt gold or Platinum a very good chance. If set in Silver or no hallmark, likely a lower grade Gem or faux.
Anything “glued in” ie no prongs or bezel (except cabochon or drilled gems) is 99% to be faux. Anything where you can see the underside of the gem is also 99% faux.
Using a loupe (x20 is better) look for inclusions. Gemstones that look perfect are much more likely to be faux.
Understanding the correct colours and tones of gemstones helps you visually sort the likely type of gemstone. Aquamarine and Blue Topaz are a different blue tone to say sapphires. Garnets are a different red tone to that of Ruby. Emeralds are a different green to Peridot.
And even with lots of experience and general testing equipment you often can’t be 100% sure that a gem is natural and not treated unless you send it to a reputable gem lab. These days the treatments and synthetic gems are of very high quality and totally like the natural gems they pretend to be. It can be a very expensive mistake to make buying treated vs untreated. Especially rubies, sapphire and jadeite.
 

Elizabethhunts

Rough_Rock
Joined
Jun 22, 2020
Messages
96
Better idea for the money to be spent on microscope or some good loupes.
Then find a website that sells lab gems for under a buck each..get atleast one of each they have around 5-6mm mosly ovals but other shapes if ovals are not available.
Then see what the have in low end naturals cheap and buy a bunch. Add some cz in different colors.
You could easily end up with 75 or so known samples for not a lot of money.
study them
Could you possibly recommend a good loupe for somebody who hasnt used one before?
I have so many loose stones already, i have a jeweler who does my fine jewelry repairs and i get my precious rocks from him- and another gem supplier whos got insanely good rates for semi- precious natural stones and i have been stocking up for jewelry making.
I will have to look into lab made, because im not sure that i have any at all (unless I do and just dont know it)
Ive probably got a group of 40-50 decent samples. Ive always used a magnifying glass to observe my sparklies, and to check for surface flaws. A loupe from what im aware has a much much higher magnification and is used for seeing the inside of the stone?
I feel like I need reading material, if anyone has any recommendations in that regard, I have kindle unlimited and even wouldnt mind ordering a paperback.
Im so in love with geology, just regular rocks even. Ive crafted with river stone for many years, and a year or two with semi- precious stones in fashion jewelry.
However, i definitely want to learn about the minerals i hold so dear. Ive learned to refine metals in the last year with the intent of making fine jewelry, but without enough background knowledge on the intricacies of gemstones, my creations have been under my own standard.
 

Elizabethhunts

Rough_Rock
Joined
Jun 22, 2020
Messages
96
I have one. It is useful for telling glass (Cubic Zirconia) from anything else. It is useful for identifying quartz varieties from Corundum or Topaz.
It can not tell you if the material is natural or made in a lab.
It can not tell you if there are treatments or filling.
Of much more use is a loupe and an understanding of what internal features different gemstones have.
Often times identifying gemstones is a multi step task.
If buying jewellery I first consider the setting and quality of manufacture. Natural gems are more likely found in hallmarked metal. If set in 18kt gold or Platinum a very good chance. If set in Silver or no hallmark, likely a lower grade Gem or faux.
Anything “glued in” ie no prongs or bezel (except cabochon or drilled gems) is 99% to be faux. Anything where you can see the underside of the gem is also 99% faux.
Using a loupe (x20 is better) look for inclusions. Gemstones that look perfect are much more likely to be faux.
Understanding the correct colours and tones of gemstones helps you visually sort the likely type of gemstone. Aquamarine and Blue Topaz are a different blue tone to say sapphires. Garnets are a different red tone to that of Ruby. Emeralds are a different green to Peridot.
And even with lots of experience and general testing equipment you often can’t be 100% sure that a gem is natural and not treated unless you send it to a reputable gem lab. These days the treatments and synthetic gems are of very high quality and totally like the natural gems they pretend to be. It can be a very expensive mistake to make buying treated vs untreated. Especially rubies, sapphire and jadeite.
I think after discussing with you all, i am more on board with getting a good loupe and resource reading material.
It seems like a gemstone identifier is more of use to those who already know gemstones, as a way of lightening the workload, so to speak.
Im not there yet.
Ive downloaded a few reads to my kindle, but I feel like asking for recommendations is a good way to get a confirmed good read on the subject of gemstone identification
 

Elizabethhunts

Rough_Rock
Joined
Jun 22, 2020
Messages
96
I had been told previously that the fog test isn't dependable due to variations in gemstone sizes and shapes and dispersion of heat rates.
Is this untrue?
 

EC8

Shiny_Rock
Joined
Jun 19, 2006
Messages
275
To be very blunt here - OP - you need to familiarize yourself with real diamonds, your confusion on other threads with rhinestones, chatons, cubic zirconia etc. is alarming. With enough experience visually differentiating diamonds from simulants isn’t that difficult, testing lab vs. mine is a whole different story but you are nowhere near there.
 

Bron357

Ideal_Rock
Premium
Joined
Jan 22, 2014
Messages
4,230
I bought myself a gem microscope and it has been so much fun. I have found lots of resource materials (free) from GIA and Lotus Gemology has wonderful photos of gem inclusions. Many other gem vendors have information sections on their websites.
I also subscribed to the International Gem Society. They have a wealth of articles and photos to help increase your knowledge. I just joined the base membership which is $75 a year. The higher membership $200 odd a year includes online courses. I am going to upgrade my membership to that so I can do their online courses. There might also be some Gemmology clubs near you, I’m joining one once this COVID stuff is over. They offer classes and help with cutting, setting gemstones and even doing some rock hunting! I’m in Australia.
 

ForteKitty

Ideal_Rock
Joined
Oct 7, 2004
Messages
4,562
I prefer the RI tester over this. This gem tester clumps different gems together and it's kinda useless.
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
9,760
I like the nikon 10x but the BelOMO 10x is a better value for a usable loop.
The BelOMO 20x is one of the few loupes sold as 20x that are anywhere near 20x.(none of them are actually 20x to my knowedge.)
You can get both BelOMOs for less than the nikon these days
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
9,760
uv light and a single white led penlight also.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
20,691
BelOMO 10x Triplet. Jewelers Loupe Magnifier 21mm (.85"). Optical Glass with Anti-Reflection Coating for a Bright, Clear and Color Correct View. Foldable Loupe for Gems, Jewelry, Coins and Trichomes https://www.amazon.com/dp/B00EXPWU8S/ref=cm_sw_r_cp_api_i_4yw-EbZFXQP46
Don’t let the low pricetag fool you.

Mitutoyo 500-196-30 Advanced Onsite Sensor (AOS) Absolute Scale Digital Caliper, 0 to 6"/0 to 150mm Measuring Range, 0.0005"/0.01mm Resolution, LCD https://www.amazon.com/dp/B00IG46NL2/ref=cm_sw_r_cp_api_i_9zw-EbZYZJX19
Best of breed.

GEMINI-20 Portable Precision Digital Milligram Scale 20g x 0.001g (Silver), GEMINI-20 https://www.amazon.com/dp/B0012TDNAM/ref=cm_sw_r_cp_api_i_yCw-EbY92Q958
There are likely better units but I’ve had mine four years and it’s been dead on the cert weight for all my diamonds.
 

sunandsky

Shiny_Rock
Joined
Jul 18, 2013
Messages
160
@bron, can you say more about open backs being mainly faux? Thank you!

I have one. It is useful for telling glass (Cubic Zirconia) from anything else. It is useful for identifying quartz varieties from Corundum or Topaz.
It can not tell you if the material is natural or made in a lab.
It can not tell you if there are treatments or filling.
Of much more use is a loupe and an understanding of what internal features different gemstones have.
Often times identifying gemstones is a multi step task.
If buying jewellery I first consider the setting and quality of manufacture. Natural gems are more likely found in hallmarked metal. If set in 18kt gold or Platinum a very good chance. If set in Silver or no hallmark, likely a lower grade Gem or faux.
Anything “glued in” ie no prongs or bezel (except cabochon or drilled gems) is 99% to be faux. Anything where you can see the underside of the gem is also 99% faux.
Using a loupe (x20 is better) look for inclusions. Gemstones that look perfect are much more likely to be faux.
Understanding the correct colours and tones of gemstones helps you visually sort the likely type of gemstone. Aquamarine and Blue Topaz are a different blue tone to say sapphires. Garnets are a different red tone to that of Ruby. Emeralds are a different green to Peridot.
And even with lots of experience and general testing equipment you often can’t be 100% sure that a gem is natural and not treated unless you send it to a reputable gem lab. These days the treatments and synthetic gems are of very high quality and totally like the natural gems they pretend to be. It can be a very expensive mistake to make buying treated vs untreated. Especially rubies, sapphire and jadeite.
 

Karl_K

Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
9,760
Mitutoyo 500-196-30 Advanced Onsite Sensor (AOS) Absolute Scale Digital Caliper, 0 to 6"/0 to 150mm Measuring Range, 0.0005"/0.01mm Resolution, LCD https://www.amazon.com/dp/B00IG46NL2/ref=cm_sw_r_cp_api_i_9zw-EbZYZJX19
Best of breed.
Yes a very very good tool but in a lot of ways overkill.
This is also very good at a fraction of the price.
But I find with digital every time I want to use them the battery is dead so I like the dial calipers for occasional use.
Finding a good metric set at a low price is not easy so im going to recommend some very very good ones.
 

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
7,393

denverappraiser

Ideal_Rock
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Joined
Jul 21, 2004
Messages
8,769
I'm a big fan of Presidium and they make fine equipment. I own several of their tools. That said, the most useful test instrument, by far, is a 10x loupe. You don't even need a $300 one unless you're really going into the business (and maybe not even then). One of those $20 triplets works just fine for most applications. Separating diamonds from CZ, corundum, and moissanite is almost always easy. There are separations that are not, like natural vs. synthetic diamond, but those multi-tester things aren't helpful for this. If I were advising a starting gemologist on what tools are required for the job, those wouldn't be in my top 10 but, if you're committed to getting one, Presidium is a good choice.
 

Sunstorm

Brilliant_Rock
Trade
Joined
Feb 5, 2014
Messages
1,688
Nah... don’t even use these. You really need the eye and experience and yes you use your eyes to tell if a stone is a diamond. But if you don’t trust yourself, don’t even try. They also tend to malfunction quite a bit. Presidium often signalled moissy when I was testing old cut melee in antiques many years ago, every time it gave a different reading. It did often have trouble with diamonds. I have not used one in many years. I would not even attempt to use it on colored stones. They can be extremely difficult. Spend your money instead on an appraiser with a reputation.
 

prs

Brilliant_Rock
Premium
Joined
Dec 26, 2017
Messages
1,167
I've had a Presidium Gem Tester II for a couple of years and find it is reliable and performs exactly as the manufacturer claims. It's relatively easy to use, and gives accurate results if you follow the manufacturers instructions, and ensure you have good contact between the probe and the surface of the gem. It has a battery back up so you can take it with you and check any gems you might want to buy at an estate sale or flea market.

It easily distinguishes diamond from glass, but cannot distinguish diamond from moissanite.

It reliably identifies different types of gemstones, but cannot distinguish between natural and synthetic gems.

Here is a photo of the dial that gives the results:

presidium scale.jpg

They have another, pen shaped version with a smaller probe. The reviews on that version were much less positive, so I decided to go with the bigger Gem Tester II and have been happy with the results.
 
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