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Torak

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  1. Thanks, I got it out with a very sharp scalpel!
  2. I recently bought a H&B sovereign and it comes in a very tight capsule which I'd like to open. I've tried using a Swiss army knife but am finding it difficult! Any advice?
  3. @augur wow those variations are quite striking actually, you'd think mints would be super accurate now days. Thanks for that.
  4. Haha I'm sure you're good! The effect is very small, so even if you caught a small movement you probably just assumed it was in the direction you expected!
  5. @PansPurse thanks. Tbh I'm not really worried about it being fake, I'm just trying to get used to measuring and understanding what is an acceptable difference. That's good to know about the occasional slight increase in weight for silver coins. Yeah I will be doing a specific gravity test at some point. Again not because I'm paticularly worried but just because I want to get some experience and have some fun with it!
  6. @silenceissilver I've just ordered some neodymium magnets so am looking forward to playing around with those. Now this probably deserves it's own topic but I'll post it here for now... My understanding is that diamagnetic materials weakly repel magnets and paramagnetic materials weakly attract magnets. So I'm not sure why the gold should be attracted to the magnet in your test, as it is diamagnetic. With the case of a changing magnetic field (in the slide test it is changing because it is moving) this causes eddy currents which produce magnetic fields which oppose this change. This explains the drag seen with silver. Different metals due to properties like conductivity will have this effect to varying degrees. Obviously ferromagnetic metals will simply stick together. I'm not sure why silver has such a strong effect and gold such a weak effect. Silver is more conducting than gold but not hugely. Still I understand the principle. I realise this is quite technical, but I'm just interested to know if anyone would know anything more about this. No worries if not, this is something I wish I'd bought up with my lecturers back in uni days!
  7. Ok I'm getting 38.67 now which is closer. If I apply a decent amount of pressure I can get it to 38.63 but after I release the pressure it jumps back up. The specified diameter is 38.61. @augur out of interest why do you allow a larger tolerance for coin thickness?
  8. Thanks for the guidance guys, really appreciate it. I'll do more measurements as in the video tomorrow.
  9. Although I'm happy buying from well known reputable dealers I think it would be a useful skill to have and would increase my peace of mind
  10. The diameter of the brit is measuring at 38.71. This is outside your 0.05 tolerance. It is from the eumint via BYB group order so I'm sure the coin is genuine. I'm just wondering if there is a particular methodology to making these measurements which I'm not quite getting correct. What I'm doing to measure diameter is putting it inbetween the calipers. Then tightening calipers so they just touch the coins sides. Then I roll the coin so that the coin centre directly aligns between the caliper edges. This pushes the calipers out a little and I know I've reached that perfect point when the calipers no longer increase their reading. Then I return the to the centre position (as I will have overshot a little to confirm I have reached the maximum reading) where calipers are just touching and push the coin forward and back to see if it is aligned perfectly in that direction. Again, if it is not perfect the calipers will increase a little. Then this is the final reading I get. Basically I'm trying to get a good understanding of how to identify fakes and being sure of genuine coins by taking accurate measurements and getting used to the acceptable levels of tolerance.
  11. I've been using a digital calliper
  12. I'm assuming the rim is what is measured when thickness is quoted. But there is still a fair bit of difference there, is that normal?
  13. Thanks So what about tolerance? I have a silver 2019 Britannia which is supposed to have a thickness of 3mm. However when measured, the rim is 3.14mm and the centre is 2.64mm.
  14. When looking at different bullion dealer websites they sometimes quote slightly different coin dimensions. They also often dont give a thickness value. Is there an official place to find these dimensions? Additionally what is the toletance or variation from these values that we can expect without being worried about having a fake?