There has been some discussion about how difficult it is to distinguish between elephant and mammoth ivory. The description on the USF&W identification page seem overly complicated to me. Here it is
http://www.fws.gov/lab/ivory_natural.php#elephant
It was written by a scientist and sometimes they take things pretty seriously. I don't think its that complicated so I did it myself and took some pictures.
This is how the mammoth ivory typically looks when we buy it. I think we can all agree, it looks nothing like elephant ivory. I think you would have go to great lengths to make elephant ivory look like mammoth ivory. I have never seen raw mammoth ivory that could have been mistaken for elephant ivory.
This is a batch of mammoth ivory scales. Mammoth ivory (bark) scales never look like elephant ivory scales unless you sand down through the exterior bark. There is no sense in doing that because there is a higher demand for the colorful scales and higher prices are generally paid for the colorful mammoth ivory scales. Down in the lower left corner is a piece of Asian elephant ivory for comparison. Next to it is a piece of interior mammoth ivory, what is sometimes called "core". That set of scales is as big as we can ever hope to get from any mammoth tusks from Alaska, occasionally we can get some big enough to make a single hidden tang knife handle from but it's pretty rare.
I think that most of us would agree that the scales, except the interior ones, could not be confused with elephant ivory. I suppose someone could try to fake the colors and make white ivory look like ancient ivory. It's pretty easy to tell when they do that because the color on real ancient ivory goes into the ivory. If it was faked, the color would only be on the surface. It's kind of like fake damascus, the texture is only on the surface, if you check the spine of a fake damascus blade it will be shiny instead of showing layers. All of this ivory is naturally colored, no stain was used anywhere.
Here's a closer look at the lower left corner.
I sanded the ends on some of the scales to 400 grit so that my camera would be able to show you the Schreger lines. I sanded about ten sets, I polished just a few of them. Out of thirty seven sets of scales, I could see the Schreger lines, what we call cross-hatching, on 31 of the sets. That was with just sanding with a 36 grit disk sander on the ends of most of them. If I had finish sanded all of them, I am sure I could have seen the lines in almost all of them, with just my naked eyes.
These pictures were all taken with my regular point-and-shoot camera, that I bought for less than $100.00. The camera was set on Macro mode.
This is one that I polished as well as sanded.
This is the set of interior mammoth ivory scales, you can see the lines pretty clearly, I used no stain or magnification on any of these.
This is the end of the piece of Asian elephant ivory. Right now it's legal to sell this. I have an affidavit from the guy I traded for it from to account for it's origin. If the federal ban on trade passes, we would not be able to sell it. You can see the lines pretty easily, again nothing fancy, no stain, no photocopy machine.
Here, I used a pointy marker to mark the mammoth ivory along the Schreger lines.
and the Asian elephant.
Then I measured it, the angles in this piece, the Asian elephant measure 103.6 degrees.
This is the interior piece of mammoth ivory. It measures 90 degrees.
This is one of the exterior scales (we call bark). It measures 79.3 degrees. Mammoth ivory bark scales are always cut from the outside of the tusk so they always work for measuring the angles. If you have interior scales or material cut from the middle of the core the angles will be even sharper so they can't be mistaken for elephant.
Anything that measures over 100 degrees should be elephant, anything that measures under 100 degrees should be ancient ivory.
I can do this with virtually every piece of ivory in my shop without any fancy equipment.
I think that only very rarely mammoth ivory could be mistaken for elephant ivory to the casual viewer but remember, our fish and wildlife personnel are not supposed to be casual viewers, they are supposed to be trained. In a very small percentage of the cases would you need a science lab to know the difference. And since most pieces of ivory art work are already polished, you should be able to see the Schreger lines without having to harm the piece in any way.
Hope this clears thing up for some of you.