Joined: Wed Sep 09, 2015 5:01 am Posts: 27 Location: Durban, South Africa
I've had this strange 10ct tourmaline for a couple years now and would like to know your thoughts on it. It has slight color change from dark grey-blue to grey-violet. It's from Mozambique. The rough had a crystal face with a very thin pink rind. I don't believe it was mined in the area that usually produces cuprian tourmaline but I guess it's possible that it could be cuprian. Unfortunately it was just the one stone, otherwise I'd have tried heating a smaller one. I do think this color is quite attractive as is though. It looks very spinel-like.
I don't quite know what to call this one or what kind of price I can put on it because I haven't seen anything similar for sale. Any ideas?
I have successfully tested mounted stones with it. The issue becomes getting a good light source through the stone. The included light housing can limit this. It is a halogen light and you can set your light baseline. So, in many cases with larger stones that don't fit in the housing, and mounted stones, you just remove the housing and position the stone so you can use a fiber optic halogen light source. The addition of a halogen light source in addition to the standard source is also sometimes required with very dark stones.
This is a very flexible tool. It does come with a limited gem database. The search/matching algorithm I find only sometimes useful. It is not a black box solution. One should be knowledgeable to use it properly.
It does have both absorption and transmission modes which I find useful. I find the transmission mode is often better for me to see patterns against the visible prism at the bottom of the screen. It is the inverse of the absorption, and the peaks become valleys right next to the prism bar. This makes it easier to visualize the absorption lines to compare to the GIA and other reference optical spectrometers pictures.
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Thanks for the response. When you mention the data base being small, how small? Also, do you use it predominately to identify trace elements like copper. or for general gem identification?
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