Generally very unreliable tools for most stones in full accuracy. Universal testers are over the counter relatively cheap quick home devices designed to help one to identify gems & diamonds. The key word is: Tool to Help in identifying stones. Universal testers are nowhere near 100% accurate and by all means, do not replace professional Gemologists, full index stone composition examination and proper gemological full examination. There is a reason why Graduate Gemologists are trained in sorting and identifying stones. You will most often still have to move further into hardness examination, full composition examination etc to get full accurate correct testing.
Universal testers are heat based analytical devices that reads stones heat composition only. The problem is most stones today are treated, close to all in the daily general gem trade. This will throw devise off. For example, if one has a heated gem stone, as most gems today are, the treatment will interfere with the testing device and often throw off its reading. Heat treated stones are tested with heat composition reading devise...machine becomes confused and show the closest reading or last reading it was able to make.
It is also advised in manufacturers owner manuals and disclaimer of these devices. One will very often get Topaz’s reading as Aquamarine and vise versa, Rubies as Spinels and vise versa, Amethysts as plain quartz (Please remember natural Amethysts are members of Quartz family in gemology). Since most color Diamonds are irradiated, radiated or heated, this will interfere with heat based testing device. You will find many discussions regarding this world wide in the trade and from collectors in the internet chat rooms. You can visit further Google search by typing in keywords: Presidium Testing Problems or universal gem testing accuracy and so on. If you are relying on universal home testing devices for 100% accuracy, you are bound to enter many conflicts with everyone.
Diamond Tester - Reliable.
Devices are testing hardness only and often are reliable. Presidium for this reason has a specific diamond tester manufactured separately. Diamond testers test Diamonds solely for hardness. Devises, whether inexpensive or expensive, are all reading stones for hardness only and ensuring the hardness is at 10 Mohs scale. Today most also exclude Moissanites from examination. Please make sure your Diamond tester has fully working batteries, the device is fully loaded and ready to be used ( most have light indicator when ready ) and that your allow device enough time to read a stone, sometimes as quickly as 20 seconds. Especially with small diamonds, you do have to fully ensure the needle is firmly steadily on the stone and will not interfere with surroundings. It is always recommended to use the metal tray that comes with most devises. Place the Diamond on the tray and this way outside objects do not interfer with the testing.
Refractometer - Reliable when correctly used with all treatments also considered. Method measures the refractive index of the gemstone, composition and physical properties. It measures the extent to which the light that passes through the gemstone from the air is bent. It helps identify the gem by comparing index with the established values. Method examines purity of the gem by comparing it to the value of a natural gemstone and the amount of solute that has been added to the gemstone by comparing the refractive index thus obtained with the standard established curve. This is done by putting a drop of a liquid with a high RI, on a glass disc which is based on the tip of the Refractometer. Natural or white light is passed through this. The RI is reflected in the magnified gauge. Please remember treatments to be calculated in, small miscalculation or considerations will through off your testing.
Polariscope - Reliable when correctly used with all treatments also considered.
Polariscope determines if a gemstone is natural or not, separates Diamonds from Moissanites and detects strains in diamonds. It differentiates gems that have double or single refraction, birefringence. Double refraction puts a ray of light into two rays, the ordinary ray and the extraordinary ray, when it passes through gems like calcite also called Iceland spar. Effect sets in gems that are anisotropic in structure - having properties differing according to the direction of measurement. The polariscope tracks the path the rays of light are taking through the tested stone. While measuring the optic characteristics of transparent to translucent gem, discovering the refractive index. Please remember treatments to be calculated in, small miscalculation or considerations will through off your testing.
Color Filter- Reliable when correctly used with all treatments also considered.
Separates natural, synthetic and imitation gem material. It helps in establishing whether similar looking stones exhibiting the same colors are natural or not. Very useful with green, red or blue gems and also detects dyes in gems. Please remember treatments to be calculated in, small miscalculation or considerations will through off your testing.
Dichroscope - Reliable when correctly used with all treatments also considered.
Dichroscope can effortlessly separate gemstones based on dichroism - property of a gemstone to show two contrasting colors when turned in two different directions, under a light. This is used to distinguish two physically similar looking gemstones. The dichroscope is used to view the dissimilar color tones of the dichroic piece. It can easily just as an example, separate a Ruby from a Tourmaline, dichroic from pleochroic. Please remember treatments to be calculated in, small miscalculation or considerations will through off your testing.
X-Rays - Reliable.
X-Rays are sometimes conducted to separate natural pearls from cultured pearls. Often you can simply test real Pearls by placing pearls to the back of your neck. If feels slightly cold to your skin, the pearls are often real.
If all testing does not give you a comfortable feeling, please consult your local Graduate Gemologist, GG for further assistance. Professionals are always happy and willing to help you at relatively low cost, if only their opinion is only needed, instead of a expensive certification. It is always the best to ask and ensure the person who you are dealing with is trade approved Graduate Gemologist, GG to ensure all is fine. Majority of the unnecessary conflicts in the gem trade worldwide are from a non graduate Gemologists giving out verbal opinions without any proper gemological examinations completed. Thank you. Verzazio.com
