Cutting Natural Rough Stones

Cutting Natural Rough Stones - Broken Rubellite
A top color piece of Nigerian Rubellite. It weighed over 20 carats… Past tense.

Everybody looses a stone once and a while. Stones break, that is just the way life is, it happens. If you’re cutting natural rough you can expect stones to break occasionally.

I finished cutting this stone late one night and it looked perfect. The next morning when I inspected the stone there was a stress fracture all the way across the pavilion of the stone.

Broken Rubellite

There was no indication of a flaw any where during cutting or after I finished the stone and cleaned all the wax off of it when I finished it before going to bed. As you can see in the picture above there was a little bit of a color zone in the tip of the pavilion of the stone.

The stone was saturated when I orientated the rough. I did see the zone and thought (hoped) it would not be a problem. Color zones like this in the Nigerian material are generally not an issue and cut and blend well.

Broken Rubellite

As you can clearly see, not this time. There was apparently some stress in the stone between the color zones and when I faceted and polished the pieces I release it. Causing the fracture.

Fractures like this usually occur when you first release the stress while roughing the stone in. It is very rare for the stress to hold off until the stone is polished. Believe me, I much prefer the stress to cause a break right away, before I spend all the cutting and polishing time I did on this stone.

But that is how it goes. This type of thing happens to everybody. So do not feel like it is just you…

About the author
Jeff R. Graham
The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.
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