Digital refractometer by Presidium (model Prim II)

Summary

Made by Presidium, the leading manufacturers of gem testing equipment.

There is downloadable software to connect it to your computer. The reading is then displayed along with a list of stones that match the reading, and you can click on each stone to see more information (constants). This saves time looking up charts.

Comes with a USB cable (connects to any computer/mobile device / USB-mains adaptor). 

Works with loose stones and also stones mounted in small items of jewellery.

USES:

- to confirm stones are as described by your supplier

- to show a customer the reading, when you already know what the stone is and just need to 'prove' it

- to sort parcels of stones to see which look 'interesting' and worthy of further investigation, and then...

...to narrow the possibilities down to a handful of stones (sometimes just 1 or 2) so that you can carry out further investigations.

Instruction manual (pdf)

Refractive Index chart (pdf)

Video (youtube)

Guide to buying electronic gem testers (web page)

Video

Pros and Cons

Advantages, as an electronic tester:- instant reading and no waiting time between tests

- tiny sensor for testing stones down to 3mm diameter

- pull-out refractive index chart as a quick-reference for diamond / diamond simulants (including Moissanite) 

- built-in 8-piece gemstone holder (sets of sample gems are an optional extra)

- use the downloadable software from Presidium (available for Windows or for Mac), see all the stones with the same refractive index, and for each stone you get to lots of additional information, to help you decide which one it is.

Disadvantages, as an electronic tester:- although mounted stones can be tested, the item of jewellery must be placed over the sensor so that the top (table) of the stone covers the hole, and this is not possible with large or 'lumpy' items of jewellery

- will test loose stones only, not mounted stones

- the surface of the stone must be perfectly flat, perfectly polished and perfectly clean.

- it is a sensitive piece of laboratory equipment, it must be kept clean and dry, the sensor must be kept dust-free, it must not be bumped in and out of bags or used on damp outside market stalls

- as with all testers, there are many stones with the same, or similar, readings

Advantages over an optical refractometer:- gives higher readings (1.00 to 3.00) and this enables it to test for diamond and for simulants such as Moissanite

- no contact fluid required

- fast and easy to use, easy-to-read digital display

- wider range of readings

- connects to software to further identify the stones.

Disadvantages over an optical refractometer:- it's not as versatile as an optical refractometer, you only get one reading for each stone (technical: you can't measure the birefringence).

- this Presidium "Digital refractometer" does measure refractive index but, technically, it is not a refractometer, it is a reflectivity meter that uses a clever computer program to calculate refractive index. You probably don't need to know that!  All you need to know is (if you are familiar with the optical refractometer) it does not show double refraction and so, for the expert, is not as flexible as an optical refractometer. 

Specifications

Range of measurement, 1.000 to 3.000

Power: one 9 Volt battery + USB (cable supplied)

Size 5 X 3 X 2 inches (125X 75 X 50mm)

Item weight 150g. 

Alternative gem testers

Please note, none of these testers will distinguish natural stones from synthetic stones. "Synthetic" is a scientific term meaning 'made by man in a factory/laboratory to the same formula found in nature', the two are usually indistinguishable. 

[1] All testers test loose stones but not all can test mounted (set in jewellery) stones.

[2] The probe / analogue meter will test mounted stones, the digital meter will only test loose stones.

[3] The probe / analogue meter: 17 stones; the digital meter: 40 stones.

[4] Skill and practice is required to use an optical refractometer, instructions are not included, see any textbook about gemmology…or the internet.   

Disclaimer

All testers  must be used in conjunction with the user's skill, knowledge and experience. Under no circumstances shall QUICKTEST be liable for direct or indirect loss sustained in connection with any item. Nothing is 100% accurate, you must understand the limitations of any tester you buy. We also suggest you regularly test known samples to check for any obvious faults. Full support given for items you buy from QUICKTEST.

Free gift details

If you would like one of the following free gifts with this product, select one from “Select your free gift” above.

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