This is the text of a post on the sawmillcreek forum about exactly the same thing:
Word of caution Clint;
Under Jerusalem law, olive trees can't be cut down. Only fallen trees and pruning's can be used for sale. As you may guess, BOW of size may be a little hard to find. About 7-9 years ago, there were several dozen pallet loads of California olive wood shipped to Israel. Now it's BOW because that's where it was re-shipped from.
Instantly, a few thousand dollars of COW is now a few million worth of BOW. Although most suppliers issue a Certificate of Authenticity...sometimes those are suspect as well.