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How does saw bases on minerals affect value?

Posted by jon ertman  
jon ertman May 28, 2009 10:55AM
I us rock saw to trim a lot of minerals from hunting hill quarry,like so many of the grossulars,because the diopside matrix is so hard if you try to trim with hammer or machine it kills alot of garnets,also i use acid to etch a lot of calcite,because there is alot nice garnet under the calcite.Jon?
Rob Woodside May 28, 2009 05:22PM
Your classic killer specimen shows no evidence of preparation. It just magically appears that way!!! In reality there's a lot of work in proper prep. Saw cuts are generally frowned on. Some matrix is so tough that sawing is required and as a locality plays out saw cuts become more frequent as quantity diminishes. Sawcuts can be disguised by grinding or using hand held "jack hammers". When trying to get a deal on a rock by pointing out all the defects, saw cuts are always mentioned. In reality they probably don't make a lot of difference to the price.
Craig Mercer May 28, 2009 11:06PM
I agree Rob, but of course it depends on where the saw marks are. If they are underneath the specimen, as a form of stand, well then it doesn't detract from the quality (price) at all. How ever if saw marks are at the front of the best viewing angle of the specimen, then that is going to effect the maximum price, for me anyway.

I find alot of the matrix specimens that come out of both Afghanistan and Pakistan have extremely heavy, and in some cases irreparable saw damage, especially the Afghanites and Lazurites.


Edited 1 time(s). Last edit at 05/28/2009 11:08PM by Craig Mercer.
NH June 01, 2009 01:58AM
I have one specimen where the saw base makes the specimen more interesting because it reveals the different minerals present in the matrix better than a broken surface would, but I think it usually has a negative effect on value/desirability. As with other aspects of mineral pricing, it depends on what the buyer is willing to pay - some dealers might price a sawed specimen lower, but if the buyer doesn't care, it won't affect the value.

I think acid etching is usually pretty widely accepted, because it's essential for some localities (eg. benitoite from Dallas Gem Mine). If all of the calcite is removed, it's also not obvious to someone not familiar with the locality, unlike a saw cut.
Rob Woodside June 01, 2009 04:20AM
Actualy it's natrolite the hides the xls at the Gem Mine.

But NH raises an interesting question: When does the value of the information given by damage outwigh the value lost by the damage? I have in mind a diamond xl in matrix showing a cleavage face or an Ongonja cuprite totally buried in Malachite. Certainly I preferred the but ends of Cobalt vein sections. The but end showed the specimen and the saw cut showed the texture- I think that actually increased the value.
Allen Steinburg June 02, 2009 01:04PM
It really come down to personal choice and what appeals to the potential purchaser. For me, as little man made damage as possible is preferable to one that has been saw trimmed. Sometimes this cannot be avoided and will not detract from the value of the specimen. I know of one person who wishes to remove some Kyanite crystals in a slab with a portable carbide saw! That doesn't work for me.
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