For those not greatly experienced in buying rough here are some basic 'general' formulas that may help.    note :  ( 5 carats  =  1 gram)

     #1     Untouched raw rough, only washed clean in an agitator for instance and not rubbed,  you should expect the final cut stone to be around 20% of the rough piece.  For example.  A 5 carat untouched rough should cut approximately a 1 carat stone, on average.

     #2     To guage if rough is priced attractively the previous 5 to 1 formula can be reversed.  For example.  An untouched rough piece bought for $10 per gram, applying #1, would give you a cost of $10 per carat for the finished stone.  #2 is then applied showing that, 5 x your original $10 per carat cost, you should be able to purchase an equivalent cut stone for $50 per carat.  ( An equivalent finished stone should be approximately 5 to 1 or 5 x your cost )

     #3     Rubs or rubbed stones that have been worked on to expose the color offer a far less risk or gamble when purchasing as you can see more easily what you are buying and also a dealer knows exactly what they are selling.  There is much less waste material and a far greater yield than buying untouched rough as in example #1, hence the cost per gram for rubs is much more.  (often between 40 - 60% of the finished stones' value)  Once you determine the cost of an equivalent cut stone you can then determine if the work left to finish the stone is worthwhile.

The above three points are an average, general, basic guide and will differ from dealer to dealer and rough to rough as 'opal always surprises'.  Sometimes rough that shows little or no visible color to anyone can yield a nice stone within and unfortunately this can work the opposite way too.  A reason why cutting and orientating opal is interesting and so much fun.  Another point to consider is whether you will be cutting conventional stones or freeforms which will increase your yield. 

And when purchasing boulder opal you must also consider that it is commercially acceptable to have ironstone or host rock exposed on the face of the finished stone.

There is no substitute for common sense and logic, this of course comes with our own personal cutting experiences.  Luckily we have advanced through the mail order catalogue times and fantastic sites like this offer us pictures to view the actual items before we buy.  However, with opal, nothing can compare with seeing it in your own hand, in natural sunlight and when you first receive a rough parcel you should always wet it and view it this way.  Lastly, always insist on a 100% Money Back Guarantee.   All good dealers who believe in their product and service know that not all rough opal is suitable to everyone, and will offer this, happily !  

" Guarantee "       

OutbackOpal's rough items are priced extremely fairly with the above hints in mind and in accordance with the wholesale guidelines of this great auction site.  The items you will receive are the items that are pictured and all opals are represented as accurately as possible.  However, it can happen that one cutters challenge can be another cutters nightmare.  So if your opinion varies and you are not happy with your purchase, you are welcome to contact us to organise a prompt safe return and refund for the entire, unused and unaltered product.  Which is no less than I would expect when making a purchase !