I've just found this product on the net called Musi-traC and sounds like quite interesting way of identifying your instrument if it is found after theft.
Musi-traC is a tiny microchip to identify and protect your musical instrument.
Inexpensive way to protect your instruments and other property
Operates throughout the UK by MIA approved Musi-traC centre
Dramatically reduces the risk of theft
Aids recovery of stolen property
Microchip Lifetime Guarantee
FREE entry on The National Register of Musical Instruments
http://www.themusictrade.co.uk/html/how_does_it_work.htm Has anyone heard of these before?
I guess if you were having a new instrument built you could send one to alembic and ask them to secure it inside the instrument during construction.
Smart Water!!
My insurance company sent me a free bottle of smart water with my last policy. You brush a bit on and it uniquely marks the instrument( invisibly) and the solution shows up when the police shine in ultra-violet light on it.
http://www.smartwater.com/Personal.aspx However i guess they are both only any good if the instrument is recovered, and to prove identity not prevention of theft.
Jazzyvee