I used to say they aren't making any more of this. These days, maybe I should say not yet. Wooly Mammoth ivory is often found below the perafrost in Northern gold mines and other excavations. It is highly prized by knife makers and collectors. All of it has value, but that value goes up with condition, size, color, preparation and matching. (You can't bookmatch a tusk the way you do with a piece of burl wood.
We have sourced mammoth over the years directly from Alaska, The Yukon and Siberia - and some has come from distribution centers from the US to the far East. Parentage isn't well known. All claim to be stabilized, but that term is not standardized.
It is not cheap but increases both the sentimental and dollar value of a knife significantly.
Pease expect some deree of warping of the scales you order. It is present on almost all sets and may require some flattening or filling on the part of the maker.