"Tree of Hapiness"? - No. "Tree of Life"... yeah. These are even posted online at the source
HERE. The design is very copied - countless versions by other jewelers sold as such or with false pretense of being the 'original'. Now, the design idea is so old, done and redone since time immemorial that Mikimoto hardly owns it (what else is new?). I am not sure if the Miki signature warrants insurance and what good an independent appraisal could do; the receipt might just be enough and since the brand name is where most value is... that is one feature that is well document and does not need expert appraisal (IMO). The pearls would wear anyway and by the time they do, the insurance premium might be more than replacement cost. Up to you, I guess.
All this wan written assuming the what you have is the pin listed there or a closely related piece. It could have been significantly more expensive in japan. I know it is more here (~E 1.2k) than the US listed price. There is a white gold version. I am not sure about silver - it does not appear on the paper catalog among the tree of life series and have never seen any on sale anywhere.... that is not perfect info though.
Guys seems to be allot more into brand name jewelry! Perhaps that gives them reassurance that their gifts will be right on target, more than their personal choices might...
Either price seems very high!