Where to buy a decent ring size mandrel and gauge rings?

[qwedsy]

I would like to buy a gauge to use at home, mainly for measuring the pre-loved rings I've bought over the years since I have no idea on the size of them. Are there differences in quality for example with the ones sold on ebay? Would this be a good one? http://www.ebay.com/itm/Aluminum-Ring-Sizer-Guage-Mandrel-Finger-Sizing-Stick-Measure-Standard-Tool-/370791686604?pt=LH_DefaultDomain_15&hash=item5654e821cc

And what about the gauge rings, have you found the ebay ones reliable?

Any other geeky stuff you would recommend for a semi-newbie diamond and ring enthusiast?
I currently own an ASET scope (with all the extras that came with it) and a lousy 10x loupe.

 

[Julia1234]

You want geeky stuff....ok, if you want to measure those rings, I can recommend a website called http://FindMyRingSize.com that lets you find the exact size of your rings for free. It works by calibrating the screen to the online chart. Good luck.

 

[ForteKitty]

If you can get the inside diameter, you can match it up here: http://en.wikipedia.org/wiki/Ring_size I use a plain ruler but I'm pretty good at eyeballing fractions of a mm. If you're not as comfortable, you can use calipers and get the exact mm.

I found that mandrels can differ from jeweler to jeweler.