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From Rough Stone to Cut Stone: Part I

Posted by Cecile Raley on

The journey from rough mineral to finished faceted gem has always fascinated me.  As a relative novice in the area, there are mostly surprises, but even the more seasoned cutter or gem expert can’t always predict the outcome.  On average one loses 60-80% of the gemstone material during cutting. Sometimes more, sometimes less.  One has to decide where the cleavages are that will open up during cutting, and one has to determine where the culet and table should be located.  The properties of the gem itself usually dictate this, though opinions on how to cut often vary nevertheless.

And so, when I saw a parcel of rough Winza sapphires at the Gem and Mineral show in Edison, NJ, this month, I decided to have some fun with it.



Winza Sapphire









In this little video, you can meet Don Thomson from Quest Minerals.  Don specializes in Tanzanian goods and he is also a gem cutter.  I was fascinated by his collection of crystals and rough as you can see.

Meet Don Thompson and his collection of gems and minerals.


As you can see, I discovered the parcel of sapphires and another of rubies at the very end.  With my curiosity peaked, I first looked at some pieces with a loupe, and then recorded a little video using my newly discovered phone scope (you can buy it at safepub.com). 

Parcel of Winza rubies magnified through a phone scope.


Roberta G. a customer or mine, was with me when we played with the rough.  I first bought a nice zebra striped one – I am thinking of keeping that piece more or less as is but polishing it so you can see the stripes better.  Then I started to look at each piece with a strong flash light to see what’s inside.  Roberta recorded me as I went through the parcel piece by piece.




                             Yvonne examines a parcel of Winza sapphires for cuttable material.


Then I selected a few pieces – getting them all was going to be expensive.  Don explained to me how to cut one of them and I’m very curious about the outcome.



                           Don Thompson explains how to cut a particular piece of Winza sapphire.

Next month, I will be sending some of the pieces to India for cutting.  Others will stay here.  I may slice one, and I may just have another roughly faceted by a local friend.  Roberta wants one piece faceted as well.  We don't think that any of the material is going to come out very clean, but it will be fun to do.


I will keep you posted how the adventure ends.

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