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Refractometer

Refractometer

Ref: REFRACT-L


Price: 195.00 Including VAT

Quantity:  

OPTIONS:

Gem ID Book £25.00 instead of £29.50 £25.00

Gemstones book £15.00 £15.00

Refractometer fluid £51.00 £51.00 incl. VAT

{Summary}
For the gemmologist the refractometer is the most important gem tester after a loupe. It measures refractive index (to whatt extent light is bent as it passes through the gemstone).

{Technical}

Approx. 5 X 3 X 2 inches.

Range: 1.30 to 1.81

Possible error in readings: +/- 0.01

Test plate made of high-refractive glass

Power: Takes 3 size LR44 batteries batteries (included).

2ml of contact fluid is included, just to get you started, but you will eventually need to buy a full bottle (10ml).

{Is it easy to use?}

BASIC OPERATION: Rest the flat polished surface of the stone on the test plate, and through the viewfinder you see a scale, part of which will be light and part of which will be dark. In between the light and dark is the 'shadow edge' that marks a reading on a scale. It's a little slow and fiddly but not too difficult to master.

ADVANCED OPERATION: Not only do you get a reading, but often you will see two shadow edges, indicating a doubly refractive stone (which, itself, is diagnostic), AND advanced users can glean further information by rotating the stone to see if either or both of the shadow edges move, and by taking minimum and maximum readings for each.

A refractometer measures refraction (bending) of light as it passes through the gemstone (like poking a stick into clear water.

Instructions:

A summary of how to use this is included, but it's very techincal and is a free translation from the Chinese. For detailed instructions of how to use this (and all gem testers) I reccomend Gem Identification Made Easy. Failing that, good words to search on the internet are, "Measuring gemstone refractive index"

Alternatively, a good book is Gem Identification Made Easy

{Limitations}

Although this is an 'easy' test because you end up with a number, and you look up the number on standard charts, you will soon discover that (as with all gem testers) there are many gemstones with the same (or overlapping) readings. A refractometer will help you narrow the possibilities to a handful (maybe one or two) stones, but it will not give an instant 100% guaranteed answer.

Some stones are out of range for this machine (their refractive indiex is too high to be measured) including some garnets, diamonds and most diamond simulants including zircon and sphene. This cannot, therefore, be used as a diamond tester.

{Extras}

This item is not supplied with instructions (actually, it is, but they are very difficult to understand). The book Gem Identification Made Easy systematically works its way through all the optical testers (and some of the electronic testers) telling you the theory behind them, what they will test, and how to use them. To get your discount on this book please order by ticking the "Optional Extra" box when you order the spectroscope.

Not as detailed, but good guide to gemstones, beautifully illustrated, is Gemstones.

2ml of contact fluid is included, just to get you started, but you will eventually need to buy a full bottle (10ml).