CALIBRATING ELECTRONIC GEM TESTERS
This page tells you about calibration, when your machine might need calibrating, what is involved if you want to do it yourself, and how much we charge to do it for you. If, after reading this page, you decide to calibrate it yourself, please ask us for the instructions. This applies to two models:
- model gemtest-P, PGT-CSE (the first picture, above, the meter with the needle) - read this page to learn about calibration.
- model gemtest-duo PDT-S7 (the third picture, above, with the analogue meter and the LED display) and you bought it from us before 2020 - read this page to learn about calibration.
There are two new models which have a computerised calibration system, so you don't need to read this page:
- model gemtest-duo PDT-II, which is what you will have if you bought one after 1 January 2020 (exactly the same as the third picture, above, but marked "DUO TESTER II", with the analogue meter and the digital display) - there is no need to read this page.
- model gemtest-duo PGI, (the second picture, above), the handheld model with the LCD display - there is no need to read this page.
WHAT IS CALIBRATION?
It's matching the reading to the measurement, i.e. the meter should point to 'ruby' if it's a ruby or 'glass' if it's glass. All measuring instruments go out of calibration given enough time or if they are bumped or dropped. This applies to any electronic measuring instrument (thermometer, weighing machine, gas detector...). They are not 'broken', they need recalibrating. You can calibrate an electronic gem tester yourself if you are very careful, or we can do it for you.
THE READINGS - DOES IT NEED RECALIBRATING?
• when testing, wait
for the tester to warm up (wait for the ‘ready’ light), place the probe
firmly on the stone, the meter tends to go too high then move lower over
the following few seconds. It’s the lower (settled) reading that counts.
So don't worry if the reading in the first three to six seconds is too
high, this does not mean it needs calibrating.
CALIBRATION OF THE THERMAL TESTER (the meter with the needle)
The manufacturers say that you should not attempt to calibrate it yourself. This is for two reasons. Firstly, very often it doesn't’t need calibrating (see above) and you will merely be calibrating it unnecessarily, and there is a high probability that you will get into a muddle and have to send it back to us in frustration. Secondly, calibrating it is very fiddly and you must be aware that if you damage the tester it cannot be repaired. WE know how to do this, so if in doubt, please contact us and we can calibrate it for you (there’s no charge if it’s under guarantee).
If you want to calibrate it yourself, here is some guidance:
• you must use a screwdriver
of the correct size, 1mm to 1.5mm.
WARNING: if you turn the screw all the way round, as if trying to ‘screw it’ you will break it, please do not return the tester to us, you have broken it; if you use the wrong screwdriver and damage the screw head, you won’t be able to adjust it, please do not return it to us, you have broken it, the damage is not covered by the guarantee. If in doubt, please stop now, send the unit and the probe back to us, we will do it for you (there’s no charge if it’s under guarantee).
NOTE: if you use a new probe, it has to be calibrated, otherwise the new probe won't work.
We have the instructions to calibrate this too, we have never had to do this, we could try. The procedure is similar to that described above, but instead of using the built-in calibration disc you must use a 0.2 carat sample of GGG (Gadolinium gallium garnet).
We can send you the calibration instructions, just ask. But please do read all of this page first, you do need to be confident that you can do it without breaking the machine.
It will need calibrating whenever you buy a new probe. When you buy a probe you will be given a choice of two prices, with or without calibration.
For calibration only
(i.e. you are not buying a new probe) these are our charges (2019), providing
you originally bought the tester from us, these prices include VAT:
Return postage is £10.00 for Special Delivery or £6.50 for Recorded Delivery
If it is under guarantee and needs calibrating, there is no charge.
QUICKTEST, Watford, WD18 8PH, Tel. 01923 220206, email info(at)quicktest.co.uk