Joined: Sun Oct 16, 2005 12:22 pm Posts: 21600 Location: San Francisco
While we appreciate the pictures you are posting, please remember this is an educational platform. Include information about your specimens. The pictures, on their own, tell us very little. Thanks for understanding.
While we appreciate the pictures you are posting, please remember this is an educational platform. Include information about your specimens. The pictures, on their own, tell us very little. Thanks for understanding.
Sorry for anything i'm missing out. I'm new here and getting use to how forum works also my pc spell checks at times as soon as I post. There also is a lot on here to catch up on.
Iolite is also from Tanzania, Name of Mine is unknown but mined in 2018, Sorry again if i'm missing bits out.
Specimens I have don't have there size recorded, Only Weight Origin and Stone name and Crystal grade.
Post subject: Re: Cordierite aka by the trade name Iolite: rough
Posted: Wed Jul 17, 2019 8:35 am
Gold Member
Joined: Thu May 12, 2016 2:18 am Posts: 1542
Just looked up the RI for Iolite in my Gem Tools Pro database. GTP tends to show the RI range with the variances built in. Basically showing the lowest, and highest being reported by different sources. This makes sure that your readings should be in the range. It also matches your findings.
GIA lab manual has 1.542 - 1.551 (+0.045/-0.011) which matches on the high side, and is slightly different on the low side.
Post subject: Re: Cordierite aka by the trade name Iolite: rough
Posted: Wed Jul 17, 2019 12:09 pm
Established Member
Joined: Mon May 20, 2019 3:47 pm Posts: 36
1bwana1 wrote:
Just looked up the RI for Iolite in my Gem Tools Pro database. GTP tends to show the RI range with the variances built in. Basically showing the lowest, and highest being reported by different sources. This makes sure that your readings should be in the range. It also matches your findings.
GIA lab manual has 1.542 - 1.551 (+0.045/-0.011) which matches on the high side, and is slightly different on the low side.
I can't find any source for 1.500.
1.5 with the end bit missing means it varies, I don't have tools double check stones and google searchers as abeck says are all over place.
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